首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8670篇
  免费   55篇
  国内免费   5篇
教育   6280篇
科学研究   872篇
各国文化   113篇
体育   448篇
综合类   11篇
文化理论   119篇
信息传播   887篇
  2021年   52篇
  2020年   55篇
  2019年   103篇
  2018年   154篇
  2017年   256篇
  2016年   298篇
  2015年   209篇
  2014年   161篇
  2013年   1509篇
  2012年   269篇
  2011年   270篇
  2010年   181篇
  2009年   150篇
  2008年   206篇
  2007年   181篇
  2006年   160篇
  2005年   782篇
  2004年   574篇
  2003年   402篇
  2002年   227篇
  2001年   126篇
  2000年   104篇
  1999年   84篇
  1998年   69篇
  1997年   74篇
  1996年   78篇
  1995年   72篇
  1994年   77篇
  1993年   71篇
  1992年   70篇
  1991年   77篇
  1990年   78篇
  1989年   78篇
  1988年   67篇
  1987年   64篇
  1986年   69篇
  1985年   55篇
  1984年   61篇
  1983年   85篇
  1982年   60篇
  1981年   60篇
  1980年   66篇
  1979年   58篇
  1978年   80篇
  1977年   63篇
  1976年   51篇
  1975年   51篇
  1973年   43篇
  1970年   48篇
  1966年   39篇
排序方式: 共有8730条查询结果,搜索用时 0 毫秒
71.
Formal models for service composition have been proposed with the variation of the requirements of service developers. Some famous models have provided checking and verification techniques and tools for the behavior of service composition. These models generally focus much on the message flow of web services and neglecting the data contained in the exchanged messages among services, which restrict the application range of these models and also the web service techniques. As new kind of services with different protocols and communication methods have appeared, it is needed to model service composition from a new view which is adapted to the new development in service area. In this paper we offer a function oriented model of service composition which treats the composite service as a software system and specify the function of services which can be directly used to the realization by service providers.  相似文献   
72.
The author articulates key stressors in the lives of families who are homeless. These stresses often combine with barriers such as lack of job opportunities and/or insensitive professionals. Strategies for helping homeless families overcome these barriers and related issues are presented.  相似文献   
73.
74.
75.
Objective: To observe the effect of Yangxueqingnao particles on rat vascular smooth muscle cell (VSMC) proliferation induced by lysophosphatidic acid (LPA). Methods: The amount of3H-TdR (3H-thymidine) admixed in cultured rat VSMC was measured and mitogen-activated protein kinase (MAPK) activity and lipid peroxidation end product malondialdehyde (MDA)content of the VSMC were assayed. Results: 1×10-9, 1×10-8, 1×10-7 mol/L LPA in a concentration dependent manner, induced the amount of 3H-TdR admixed, MAP kinase activity, and MDA content of the cultured rat VSMC to increase. However, 5%, 10%,and 15% Yangxueqingnao serum preincubation resulted in a decrease of 23.0%, 42.0%, and 52.0% (P<0.01) respectively in the amount of 3H-TdR admixed, a decline in VSMC MAP kinase activity of 13.9% (P<0.05), 29.6% (P<0.01), and 48.9% (P<0.01)respectively, and also, a decrease in MDA content of VSMC of 19.4%, 24.7%, and 43.2% (P<0.01) respectively, in the 1×10-7mol/L LPA-treated VSMC. Conclusions: LPA activates the proliferation and lipid peroxidation of VSMC in a concentration dependent manner. The LPA-induced VSMC proliferation is related to the activity of MAP kinases, enzymes involved in an intracellular signalling pathway. The results of the present study showed that Yangxueqingnao particles can effectively inhibit LPA-induced VSMC proliferation, MAP kinase activation, and reduce lipid peroxidative lesion.  相似文献   
76.
This investigation analyzed goals from the Individual Educational Programs (IEPs) of 54 high school students with diagnosed reading disabilities in basic skills (decoding and/or word identification). Results showed that for 73% of the students, the IEPs written when they were in high school failed to specify any objectives regarding their acute difficulties with basic skills. IEPs from earlier points in the students’ educations were also reviewed, as available. For 23 of the students, IEPs were present in the students’ files for three time points: elementary school (ES), middle school (MS), and high school (HS). Another 20 students from the sample of 54 had IEPs available for two time points (HS and either MS or ES). Comparisons with the IEPs from younger years showed a pattern of decline from ES to MS to HS in the percentage of IEPs that commented on or set goals pertaining to weaknesses in decoding. These findings suggest that basic skills deficits that persist into the upper grade levels are not being sufficiently targeted for remediation, and help explain why older students frequently fail to resolve their reading problems.  相似文献   
77.
78.
Objective: To investigate the effect of interleukin-18 (IL-18) on immune response induced by plasmid encoding hepatitis B virus middle protein antigen and to explore new strategies for prophylactic and therapeutic HBV DNA vaccines. Methods: BALB/c mice were immunized with pCMV-M alone or co-immunized with pcDNA3-18 and pCMV-M and then their sera were collected for analysing anti-HBsAg antibody by ELISA; splenocytes were isolated for detecting specific CTL response and cytokine assay in vitro. Results: The anti-HBs antibody level of mice co-immunized with pcDNA3-18 and pCMV-M was slightly higher than that of mice immunized with pCMV-M alone, but there was not significantly different (P>0.05). Compared with mice injected with pCMV-M, the specific CTL cytotoxity activity of mice immunized with pcDNA3-18 and pCMV-M was significantly enhanced (P<0.05) and the level of IFN-γ in supernatant of splenocytes cultured with HBsAg in vitro was significantly elevated (P<0.05) while the level of IL-4 had no significant difference (P>0.05). Conclusion: The plasmid encoding IL-18 together with HBV M gene DNA vaccines may enhance specific TH1 cells and CTL cellular immune response induced in mice, so that IL-18 is a promising immune adjuvant.  相似文献   
79.
Rats were trained to leverpress for food and subsequently exposed to either arithmetic series or random variable-interval reinforcement schedules. Adjunctive drinking developed in all subjects exposed to arithmetic variable-interval reinforcement, but did not develop in six of the eight animals trained on the random schedule. The results suggest that adjunctive drinking is the result of an interaction between the tendency of rats to drink after eating and the ability of locally low probabilities of reinforcement within schedules to induce conditioned behavioral states.  相似文献   
80.
In order to emphasize the development of skills in helping the culturally disadvantaged, graduate students were given practicum placement in a Department of Labor-financed agency which gave counseling and employment training to disadvantaged youth. Students attended staff meetings, interviewed staff members concerning the work they performed, and discussed client contacts with caseworkers, in addition to interviewing agency clients. Increased awareness of problems, broadened conceptualizations, and expansion of interpersonal skills were seen as advantages of the practicum. Limitations included some lack of goal clarity and inefficiency of time use in dealing with this clientele.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号