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   8879篇
  免费   611篇
  国内免费   78篇
耳鼻咽喉   75篇
儿科学   325篇
妇产科学   200篇
基础医学   1147篇
口腔科学   149篇
临床医学   771篇
内科学   2026篇
皮肤病学   219篇
神经病学   652篇
特种医学   548篇
外科学   1552篇
综合类   83篇
一般理论   4篇
预防医学   634篇
眼科学   150篇
药学   488篇
  1篇
中国医学   37篇
肿瘤学   507篇
  2023年   56篇
  2022年   84篇
  2021年   211篇
  2020年   141篇
  2019年   210篇
  2018年   223篇
  2017年   175篇
  2016年   179篇
  2015年   181篇
  2014年   240篇
  2013年   344篇
  2012年   446篇
  2011年   511篇
  2010年   318篇
  2009年   317篇
  2008年   404篇
  2007年   472篇
  2006年   361篇
  2005年   396篇
  2004年   328篇
  2003年   353篇
  2002年   306篇
  2001年   253篇
  2000年   304篇
  1999年   244篇
  1998年   147篇
  1997年   154篇
  1996年   155篇
  1995年   121篇
  1994年   106篇
  1993年   93篇
  1992年   161篇
  1991年   152篇
  1990年   142篇
  1989年   135篇
  1988年   122篇
  1987年   112篇
  1986年   130篇
  1985年   114篇
  1984年   61篇
  1983年   59篇
  1982年   43篇
  1981年   45篇
  1980年   35篇
  1979年   45篇
  1978年   32篇
  1977年   30篇
  1976年   37篇
  1975年   39篇
  1973年   37篇
排序方式: 共有9568条查询结果,搜索用时 15 毫秒
61.
62.
63.
Increased antiphospholipid antibody prevalence has been demonstrated by a number of recent studies in in-vitro fertilization (IVF) patients but the potential effects of antiphospholipid antibodies on the different components of the reproductive process and the consideration of whether to test IVF patients for antiphospholipid antibodies are controversial. The present study was undertaken to investigate the possible association between the presence of circulating antiphospholipid antibodies (namely the lupus anticoagulant and anticardiolipin antibodies), among a series of 21 consecutive IVF patients having a clinical spontaneous abortion after their first embryo transfer. As a control group (n=42), the nearest IVF cycle resulting in an ongoing pregnancy before and after each miscarried IVF cycle (i.e. the closest cycles in temporal relationship to the index cycle) was used. One patient (4.8%) in the study group and two women (4.8%) among controls were seropositive for antiphospholipid antibodies. These low and similar seropositivity rates found in the two groups studied lead us to conclude that antiphospholipid antibodies testing in IVF patients should be considered only in those women having repeated failures of implantation/clinical abortion after embryo transfer but not in an infertile general population reaching an IVF programme.   相似文献   
64.
Our goal is to identify the genetic underpinnings of bicuspid aortic valve and aortopathy in Turner syndrome. We performed whole exome sequencing on 188 Turner syndrome study subjects from the GenTAC registry. A gene‐based burden test, SKAT‐O, was used to evaluate the data using bicuspid aortic valve (BAV) and aortic dimension z‐scores as covariates. This revealed that TIMP3 was associated with BAV and increased aortic dimensions at exome‐wide significance. It had been previously shown that genes on chromosome Xp contribute to aortopathy when hemizygous. Our analysis of Xp genes revealed that hemizygosity for TIMP1, a functionally redundant paralogue of TIMP3, increased the odds of having BAV aortopathy compared to individuals with more than one TIMP1 copy. The combinatorial effect of a single copy of TIMP1 and TIMP3 risk alleles synergistically increased the risk for BAV aortopathy to nearly 13‐fold. TIMP1 and TIMP3 are tissue inhibitors of matrix metalloproteinases (TIMPs) which are involved in development of the aortic valve and protection from thoracic aneurysms. We propose that the combination of TIMP1 haploinsufficiency and deleterious variants in TIMP3 significantly increases the risk of BAV aortopathy in Turner syndrome, and suggest that TIMP1 hemizygosity may play a role in euploid male aortic disease.  相似文献   
65.
66.
A semisolid urea-motility-indole medium designed for detection in Enterobacteriaceae of urease activity, motility, and indole production in one tube was prepared and evaluated. The formulation of the medium was similar to that of Christensen urea agar, but the agar concentration was 0.2%, and 1% tryptone was added. Results with 687 strains of Enterobacteriaceae were the same as those obtained with standard test media (98% overall agreement). The urea-motility-indole medium was also used in combination with Kligler iron agar for the recognition and differentiation of Salmonella and Shigella species from colonies picked from plating media in fecal cultures. This combination was compared with the combination of Kligler iron agar and lysine iron agar with 507 strains of non-lactose-fermenting Enterobacteriaceae. Although both combinations enabled the presumptive recognition and differentiation of Salmonella and Shigella species, an analysis of data indicated that the combination of Kligler iron agar and urea-motility-indole medium performed better than the combination of Kligler iron agar and lysine iron agar in detecting Salmonella and Shigella species.  相似文献   
67.
A review of sixty-two technetium scrotal scans performed over a one-year period has led to a classification of pathologic states based on the degree of uptake of the radioactive isotope. Absent uptake, or a "cold" scan, is present only with testicular torsion, and rarely with avascular tumors. Increased uptake, or a "hot" scan, is most commonly seen with inflammatory conditions such as acute epididymitis and orchitis, and less commonly with tumor. "Mixed" scans can be associated with abscess, tumor with necrosis, trauma, and late torsion.  相似文献   
68.
BackgroundIn this COVID‐19 era, we need to rethink the criteria used to measure the results of person‐centred care strategies.ObjectiveTo identify priorities, and criteria that health services can use to pursue actually the goal of achieving person‐centred care.DesignThree‐phase online qualitative study performed during May–July of 2020 using the Delphi technique.Setting and ParticipantsAn online platform was used for a consensus meeting of 114 participants, including health planning experts, health‐care institution managers, clinicians and patients.Main Outcome MeasuresCriteria and indicators for the achievement of person‐centred care.Main ResultsThe first round began with 125 proposals and 11 dimensions. After the second round, 28 ideas reached a high level of consensus among the participants. Ultimately, the workgroup agreed on 20 criteria for goals in the implementation of person‐centred care during the COVID‐19 era and 21 related indicators to measure goal achievement.DiscussionNine dimensions and 28 priorities were identified. These priorities are also in accordance with the quadruple aim approach, which emphasizes the need for care for health‐care professionals, without whom it is impossible to achieve a better quality of care.ConclusionsPerson‐centred care continues to be a key objective. However, new metrics are needed to ensure its continued development during the restoration of public health services beyond the control of COVID‐19.Patient or Public ContributionTwelve professionals and patient representatives participated voluntarily in the construction of the baseline questionnaire and in the selection of the criteria and indicators using an online platform for consensus meetings.  相似文献   
69.
This article presents an optimal control strategy (OCS) for semiactive vehicle suspensions with road profile sensors. The suspension is modeled as a quarter‐car model with a magnetorheological (MR) damper. The OCS main objective is to minimize the fourth‐power acceleration of the sprung mass. In addition, three pointwise constraints of the model are taken into account when the optimal control problem is solved: suspension travel limits (upper and lower) and tyre vertical force. In order to deal with a large number of constraints, we implement the gradient optimization method based on the method of moving asymptotes routine, which shows very good performance reaching optimal controls while satisfying the constrains. The solution has been compared with two passive MR damper configurations (low and high damping) as well as Skyhook and Balance control strategies for three different road inputs. Results show that OCS fulfills the constraints and reduces the sprung mass acceleration peak and the root‐mean‐quad acceleration up to 59% , in comparison to passive strategies.  相似文献   
70.
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