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   9015篇
  免费   653篇
  国内免费   23篇
耳鼻咽喉   74篇
儿科学   257篇
妇产科学   255篇
基础医学   1411篇
口腔科学   185篇
临床医学   1040篇
内科学   1736篇
皮肤病学   243篇
神经病学   1185篇
特种医学   236篇
外国民族医学   3篇
外科学   725篇
综合类   68篇
一般理论   9篇
预防医学   802篇
眼科学   304篇
药学   562篇
中国医学   20篇
肿瘤学   576篇
  2023年   74篇
  2022年   104篇
  2021年   210篇
  2020年   189篇
  2019年   219篇
  2018年   274篇
  2017年   217篇
  2016年   229篇
  2015年   279篇
  2014年   309篇
  2013年   471篇
  2012年   753篇
  2011年   734篇
  2010年   381篇
  2009年   352篇
  2008年   652篇
  2007年   596篇
  2006年   560篇
  2005年   530篇
  2004年   496篇
  2003年   464篇
  2002年   455篇
  2001年   77篇
  2000年   53篇
  1999年   72篇
  1998年   86篇
  1997年   75篇
  1996年   71篇
  1995年   47篇
  1994年   50篇
  1993年   43篇
  1992年   43篇
  1991年   37篇
  1990年   23篇
  1989年   21篇
  1988年   27篇
  1987年   23篇
  1986年   25篇
  1985年   21篇
  1984年   25篇
  1983年   22篇
  1982年   27篇
  1980年   17篇
  1979年   14篇
  1978年   24篇
  1977年   16篇
  1976年   14篇
  1975年   15篇
  1971年   14篇
  1968年   14篇
排序方式: 共有9691条查询结果,搜索用时 33 毫秒
121.
122.
Tumor cells have the ability to exploit stromal cells to facilitate metastasis. By using malignant melanoma as a model, we show that the stroma adjacent to metastatic lesions is enriched in the known metastasis-promoting protein S100A4. S100A4 stimulates cancer cells to secrete paracrine factors, such as inflammatory cytokines IL8, CCL2 and SAA, which activate stromal cells (endothelial cells and monocytes) so that they acquire tumor-supportive properties. Our data establishes S100A4 as an inducer of a cytokine network enabling tumor cells to engage angiogenic and inflammatory stromal cells, which might contribute to pro-metastatic activity of S100A4.  相似文献   
123.
The Klebsiella oxytoca lipoprotein PulS might function as either or both a pilot and a docking factor in the outer membrane targeting and assembly of the Type II secretion system secretin PulD. In the piloting model, PulS binds to PulD monomers and targets them to the outer membrane via the lipoprotein sorting pathway components LolA and LolB. In this model, PulS also protects the PulD monomers from proteolysis during transit through the periplasm. In the docking model, PulS is targeted alone to the outer membrane, where it acts as a receptor for PulD monomers, allowing them to accumulate and assemble specifically in this membrane. PulS was shown to dissociate from and/or re-associate freely with PulD multimers in zwitterionic detergent, making it difficult to determine whether PulS remains associated with PulD dodecamers in the outer membrane by co-purification. However, PulD protomers in the dodecamer were shown to be stable in the absence of PulS, indicating that PulS is only required to protect the protease-susceptible monomer. DegP was identified as one of the proteases that could contribute to PulD degradation in the absence of PulS. Studies on the in vitro assembly and targeting of PulD into Escherichia coli membrane vesicles demonstrated its strong preference to insert into the inner membrane, as is the case in vivo in the absence of PulS. However, PulD could be targeted to outer membrane fragments in vitro if they were preloaded with PulS, indicating the technical feasibility of the docking model. We conclude that both modes of action might contribute to efficient outer membrane targeting of PulD in vivo, although the piloting function is likely to predominate.  相似文献   
124.
Health related quality of life (HRQoL) of living kidney donors on average is good, but some donors experience a low HRQoL after donation. This study assessed the prevalence of reduced HRQoL and explored associations with pre‐ and post‐donation variables. 316 donors (response rate 74%) who donated a kidney between 1997 and 2009 filled in a questionnaire. HRQoL was measured using the Short‐Form 36; fatigue using the Multidimensional Fatigue Inventory; societal participation using the Utrecht Scale for Evaluation of Rehabilitation‐Participation. Donors on average had better HRQoL than the general population. However, 12% had a reduced physical (PCS) and 18% a reduced mental (MCS) HRQoL. Donors with reduced HRQoL reported greater fatigue (P < 0.01), lower societal participation (P < 0.01) and showed a trend towards statistical significance in experiencing more donor–recipient relationship changes (P = 0.07). Prior to donation, donors with reduced PCS had a higher BMI (P < 0.05) and more often smoked (P < 0.05). Donors with reduced MCS had higher expectations (P < 0.05). Reduced HRQoL is associated with higher BMI, smoking and higher expectations prior to donation. These results may be used to develop a screening instrument to select donors at high risk for reduced HRQoL.  相似文献   
125.
126.
127.
Many surgeons recommend rest and restricting activities to their patients after surgery. The aim of this review is to summarize the literature regarding types of activities gynecologic surgeons restrict and intra-abdominal pressure during specific activities and to provide an overview of negative effects of sedentary behavior (rest). We searched PubMed and Scopus for years 1970 until present and excluded studies that described recovery of activities of daily living after surgery as well as those that assessed intra-abdominal pressure for other reasons such as abdominal compartment syndrome and hypertension. For our review of intra-abdominal pressure, we excluded studies that did not include a generally healthy population, or did not report maximal intra-abdominal pressures. We identified no randomized trial or prospective cohort study that studied the association between postoperative activity and surgical success after pelvic floor repair. The ranges of intra-abdominal pressures during specific activities are large and such pressures during activities commonly restricted and not restricted after surgery overlap considerably. There is little concordance in mean peak intra-abdominal pressures across studies. Intra-abdominal pressure depends on many factors, but not least the manner in which it is measured and reported. Given trends towards shorter hospital stays and off work intervals, which both predispose women to higher levels of physical activity, we urge research efforts towards understanding the role of physical activity on recurrence of pelvic organ prolapse and urinary incontinence after surgery.  相似文献   
128.
129.
The objective of this study is to establish whether there is an association between the presence of FCGR3A V(176) polymorphism with SLE or its manifestations. We included 94 patients according to the 1982 ACR criteria as well as 98 controls matched by age and gender. The 11 ACR diagnostic criteria were analyzed on the clinical files. The polymorphism FCGR3A V(176) was determined by direct sequencing. There was not an association between the polymorphism FCGR3A V(176) with SLE or its main manifestations. The allelic frequency for F(176) was: 0.80 and 0.72 in cases and controls, respectively (P?=?0.09, IC95%: 0.42?C1.07); and the genotypic frequency in the group of cases was: 0.65 for homozygotes F(176)/F(176), 0.30 for heterozygotes and 0.05 for the homozygotes V(176)/V(176), while for the control group it was 0.53, 0.39 and 0.08, respectively. The polymorphism FCGR3A V(176) is not associated with SLE or any of its manifestations in patients with SLE from the West of Mexico.  相似文献   
130.
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