全文获取类型
收费全文 | 4936篇 |
免费 | 78篇 |
国内免费 | 20篇 |
专业分类
教育 | 3339篇 |
科学研究 | 631篇 |
各国文化 | 29篇 |
体育 | 379篇 |
综合类 | 6篇 |
文化理论 | 33篇 |
信息传播 | 617篇 |
出版年
2022年 | 34篇 |
2021年 | 45篇 |
2020年 | 85篇 |
2019年 | 120篇 |
2018年 | 154篇 |
2017年 | 192篇 |
2016年 | 154篇 |
2015年 | 116篇 |
2014年 | 157篇 |
2013年 | 780篇 |
2012年 | 133篇 |
2011年 | 136篇 |
2010年 | 121篇 |
2009年 | 102篇 |
2008年 | 113篇 |
2007年 | 134篇 |
2006年 | 103篇 |
2005年 | 72篇 |
2004年 | 86篇 |
2003年 | 79篇 |
2002年 | 62篇 |
2001年 | 104篇 |
2000年 | 130篇 |
1999年 | 89篇 |
1998年 | 72篇 |
1997年 | 63篇 |
1996年 | 62篇 |
1995年 | 42篇 |
1994年 | 45篇 |
1993年 | 33篇 |
1992年 | 75篇 |
1991年 | 68篇 |
1990年 | 60篇 |
1989年 | 62篇 |
1988年 | 74篇 |
1987年 | 58篇 |
1986年 | 78篇 |
1985年 | 70篇 |
1984年 | 55篇 |
1983年 | 69篇 |
1982年 | 53篇 |
1981年 | 40篇 |
1980年 | 29篇 |
1979年 | 52篇 |
1978年 | 49篇 |
1977年 | 37篇 |
1976年 | 41篇 |
1975年 | 31篇 |
1974年 | 33篇 |
1973年 | 33篇 |
排序方式: 共有5034条查询结果,搜索用时 15 毫秒
201.
The need to provide bibliographic access to a collection of original medical illustrations led the Library of the University of California, San Francisco, to search for a bibliographic control system and, not finding a satisfactory one, to develop one of its own, Part 1 of the report details the planning for such a development, including the need for bibliographic control of illustrations, the goals of the proposed system, design decisions and changes required, the type of system chosen, special subjects indexing needs, the required output, and staffing and budgetary needs. 相似文献
202.
203.
Terry N. Clark 《Minerva》1970,8(1-4):599-601
204.
205.
Academic medical librarians responsible for monograph acquisition face a challenging task. From the plethora of medical monographs published each year, academic medical librarians must select those most useful to their patrons. Unfortunately, none of the selection tools available to medical librarians are specifically intended to assist academic librarians with medical monograph selection. The few short core collection lists that are available are intended for use in the small hospital or internal medicine department library. As these are the only selection tools available, however, many academic medical librarians spend considerable time reviewing these collection lists and place heavy emphasis on the acquisition of listed books. The study reported here was initiated to determine whether the circulation of listed books in an academic library justified the emphasis placed on the acquisition of these books. Circulation statistics for "listed" and "nonlisted" books in the hematology (WH) section of Indiana University School of Medicine's Ruth Lilly Medical Library were studied. The average circulation figures for listed books were nearly two times as high as the corresponding figures for the WH books in general. These data support the policies of those academic medical libraries that place a high priority on collection of listed books. 相似文献
206.
207.
Fatigue represents a reduction in the capability of muscle to generate force. The aim of the present study was to establish the effects of exercise that simulates the work rate of competitive soccer players on the strength of the knee extensors and knee flexors. Thirteen amateur soccer players (age 23.3+/-3.9 years, height 1.78+/-0.05 m, body mass 74.8+/-3.6 kg; mean+/-s) were tested during the 2000-2001 soccer season. Muscle strength of the quadriceps and hamstrings was measured on an isokinetic dynamometer. A 90 min soccer-specific intermittent exercise protocol, incorporating a 15 min half-time intermission, was developed to provide fatiguing exercise corresponding in work rate to a game of soccer. The exercise protocol, performed on a programmable motorized treadmill, consisted of the different intensities observed during soccer match-play (e.g. walking, jogging, running, sprinting). Muscle strength was assessed before exercise, at half-time and immediately after exercise. A repeated-measures analysis of variance showed significant reductions (P < 0.001) in peak torque for both the quadriceps and hamstrings at all angular velocities (concentric: 1.05, 2.09, 5.23 rad x s(-1); eccentric: 2.09 rad x s(-1)). The peak torque of the knee extensors (KE) and knee flexors (KF) was greater before exercise [KE: 232+/-37, 182+/-34, 129+/-27, 219+/-41 N x m at 1.05, 2.09 and 5.23 rad x s(-1) (concentric) and 2.09 rad x s(-1) (eccentric), respectively; KF: 126+/-20, 112+/-19, 101+/-16, 137+/-23 N x m] than at half-time (KE: 209+/-45, 177+/-35, 125+/-36, 214+/-43 N x m; KF: 114+/-31, 102+/-20, 92+/-15, 125+/-25 N x m) and greater at half-time than after exercise (KE: 196+/-43, 167+/-35, 118+/-24, 204+/-43 N x m; KF: 104+/-25, 95+/-21, 87+/-13, 114+/-27 N x m). For the hamstrings:quadriceps ratio, significant changes were found (P < 0.05) for both legs, the ratio being greater before than after exercise. For fast:slow speed and left:right ratios, no significant changes were found. We conclude that there is a progressive reduction in muscle strength that applies across a range of functional characteristics during exercise that mimics the work rate in soccer. 相似文献
208.
Grant SJ Oommen G McColl G Taylor J Watkins L Friel N Watt I McLean D 《Journal of sports sciences》2003,21(12):1009-1015
Different methods of ball carrying can be used when a player runs with the ball in rugby union. We examined how three methods of ball carrying influenced sprinting speed: using both hands, under the left arm and under the right arm. These methods were compared with running without the ball. Our aim was to determine which method of ball carrying optimizes sprinting speed. Altogether, 48 rugby union players (age 21 +/- 2 years, height 1.83 +/- 0.1 m, body mass 85.3 +/- 12 kg, body fat 14 +/- 5%; mean +/- s) were recruited. The players performed twelve 30-m sprints in total (each player performed three trials under each of three methods of carrying the ball and sprinting without the ball). The design of the study was a form of Latin rectangle, balanced across the trial order for each of the methods and for pairwise combinations of the methods in blocks of four per trial. Each sprint consisted of a 10-m rolling start, followed by a 20-m timed section using electronic timing gates. Compared with sprinting 20 m without the ball (2.58 +/- 0.16 s), using both hands (2.62 +/- 0.16 s) led to a significantly slower time (P < 0.05). Sprinting 20 m with the ball under the left arm (2.61 +/- 0.15 s) or under the right arm (2.60 +/- 0.17 s) was significantly quicker than when using 'both hands' (P < 0.05), and both these methods were significantly slower than when running without the ball (P < 0.05). Accordingly, running with the ball in both hands led to the greatest decrement in sprinting performance, although carrying the ball under one arm also reduced the players' sprinting ability. Our results indicate that to gain a speed advantage players should carry the ball under one arm. 相似文献
209.
For activities such as squash, badminton and fencing, the ability to quickly complete a lunge and return to the start or move off in another direction is critical for success. Determining which strength qualities are important predictors of lunge performance was the focus of this study. Thirty-one male athletes performed: (1) a unilateral maximal squat (one-repetition maximum, 1-RM) and unilateral jump squat (50% 1-RM) on an instrumented supine squat machine, and (2) a forward lunge while attached to a linear transducer. We performed stepwise multiple regression analysis with lunge performance as the dependent variable and various strength, flexibility and anthropometric measures as the independent variables. From the many strength and power measures calculated, time to peak force was the best single predictor of lunge performance, which accounted for 55% of the explained variance. The best three-variable model for predicting lunge performance accounted for 76-85% of the explained variance. The models differed, however, according to whether lunge performance was expressed relative to body mass (time to peak force, mean power and relative strength = 76%) or taken as an absolute value (time to peak force, leg length and flexibility = 85%). We conclude that one to two trials were reliable for strength diagnosis and that one strength measure cannot accurately explain functional performance because other factors, such as body mass, flexibility and leg length, have diverse effects on the statistical models. 相似文献
210.
In June 2000, the Biomedical Library at the University of South Alabama introduced Prospero, an electronic desktop document delivery service. From June 2000 to November 2002, Prospero delivered 28% of interlibrary loan requests and 72% of document delivery requests. In November 2002, the library conducted a user satisfaction survey of the Prospero service. Forty-two surveys were used. Fifteen responses were received from affiliated faculty, staff, and students, who generally expressed satisfaction with the service. Twenty-seven responses were received from unaffiliated users, comprised of medical libraries, individual users, and businesses. Based on the survey results, the library deemed the Prospero service a success. To better support users, the library's Web page was updated to include hardware and software requirements for successful use of the Prospero service, as well as screen shots of the Prospero process. 相似文献