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   46883篇
  免费   4154篇
  国内免费   99篇
耳鼻咽喉   526篇
儿科学   1366篇
妇产科学   1069篇
基础医学   6051篇
口腔科学   1058篇
临床医学   5428篇
内科学   8911篇
皮肤病学   736篇
神经病学   4914篇
特种医学   2256篇
外国民族医学   4篇
外科学   6347篇
综合类   773篇
一般理论   34篇
预防医学   4418篇
眼科学   1180篇
药学   3164篇
  2篇
中国医学   55篇
肿瘤学   2844篇
  2021年   590篇
  2019年   557篇
  2018年   654篇
  2017年   554篇
  2016年   560篇
  2015年   657篇
  2014年   878篇
  2013年   1428篇
  2012年   1951篇
  2011年   2051篇
  2010年   1167篇
  2009年   1066篇
  2008年   1842篇
  2007年   2086篇
  2006年   1949篇
  2005年   1846篇
  2004年   1799篇
  2003年   1671篇
  2002年   1712篇
  2001年   1535篇
  2000年   1563篇
  1999年   1382篇
  1998年   592篇
  1997年   572篇
  1996年   569篇
  1995年   513篇
  1994年   453篇
  1993年   394篇
  1992年   1170篇
  1991年   1178篇
  1990年   1109篇
  1989年   1122篇
  1988年   936篇
  1987年   1059篇
  1986年   993篇
  1985年   995篇
  1984年   766篇
  1983年   628篇
  1982年   405篇
  1981年   373篇
  1980年   379篇
  1979年   707篇
  1978年   534篇
  1977年   453篇
  1976年   469篇
  1975年   407篇
  1974年   522篇
  1973年   457篇
  1972年   383篇
  1971年   363篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Numerous surgical procedures have been described to reimplant the ureter into the bladder during renal transplantation. Since November 1985 we have used a modified extravesical technique in 19 children. At the time of transplantation patient age ranged from 2 to 17 years (average age 10 years). Of these patients only 2 received a cadaveric kidney. Postoperative followup ranged from 4 to 54 months (average 32 months). No immediate or delayed urological complications were noted, and all but 1 graft has continued to function. This procedure is not only expeditious and safe but it also eliminates a long cystostomy suture line and requires a short ureteral length. Urinary leakage and ureteral obstruction, 2 of the most common urological complications, have not been observed in our patients. Although further experience and longer followup are required, this technique has become our procedure of choice for ureteral reimplantation in children undergoing renal transplantation.  相似文献   
82.
We have advanced the hypothesis that the primary autolymphoproliferative response of dog T cells in mixed lymphocyte kidney cultures (MLKC) results from their recognition of tissue-specific (kidney-associated) antigen(s) presented in conjunction with class II MHC antigens. Lymphocyte culture-derived supernatants had been found previously to upregulate class II antigen expression on kidney cells and enhance T cell activation. In the present study we have isolated and characterized dog IFN-gamma, a class II-inducing substance that is secreted in the culture supernatant of activated T lymphocytes. Dog IFN-gamma was induced with A-23187 and PMA and purified stepwise using controlled-pore glass, Mono Q anion exchange chromatography, and Superose 6-gel filtration on FPLC. The purification resulted in two molecules of 42 Kd and 31 Kd molecular weights. An IgG1 monoclonal antibody was engendered to these molecules. With this mAb reagent, in immunochemical experiments, we have developed a sensitive ELISA and a method for purifying dog IFN-gamma by affinity chromatography. Species specificity studies indicated that purified dog IFN-gamma reacted with a polyclonal rabbit antihuman IFN-gamma, but not with a mAb to human IFN-gamma. However, the antidog IFN-gamma mAb that was generated also reacted with recombinant human IFN-gamma. In in vitro biological studies, the purified IFN-gamma (two mol. wt. species) upregulated the expression of canine class II MHC molecules on dog tubular epithelial cells and the dog kidney epithelial cell line (MDCK). The antidog IFN-gamma mAb blocked T cell proliferative response to kidney cell and, by inference, the interaction between endogenously released IFN-gamma in vitro with its cell surface receptor, thus inhibiting the induced upregulation of class II. Interestingly, although antidog IFN-gamma markedly blocked the MLKC (10 micrograms mAb/well), there was no effect on the allogeneic MLC. This observation indicates that the cytokine IFN-gamma may be a uniquely key substance amplifying the immune response of T cells to tissue-associated antigens on surrogate antigen-presenting cells that require induced upregulation of class II MHC antigen expression (MLKC), in contrast to reactions in which these antigens are already constitutively expressed on the antigen-presenting cells (mixed lymphocyte culture).  相似文献   
83.
84.
85.
As the human immunodeficiency virus (HIV) epidemic continues there are increasing numbers of patients with HIV-related disease. Doctors studying for the MRCP exam will need to be familiar with the common manifestations of HIV infection and acquired immunodeficiency syndrome.  相似文献   
86.
87.
88.
Depression is common in Parkinson's disease (PD) and affects 30 to 50% of all patients. In contrast to the wealth of research on depression in PD, little is known about the occurrence of depression in other movement disorders. The primary objective of the current study was to determine whether the high prevalence of depression symptoms seen in PD is also found in other movement disorders, by directly comparing rates of specific depression symptoms and depression severity across PD, dystonia, and essential tremor (ET). Three hundred and fifty-four patients with PD, 83 patients with dystonia, and 53 patients with ET completed the Beck Depression Inventory (BDI). We found no significant between-groups differences for depression severity, frequency, or endorsement of specific depression symptoms. Forty-eight percent of PD patients, 37.3% of dystonia patients, and 34% of ET patients were found to be at least mildly depressed (BDI score of 10 or higher). The most commonly endorsed symptoms were fatigability, difficulty with work, anhedonia, and sleep disturbance. Clinicians should be aware that depression is a frequent problem in dystonia and ET, in addition to PD, and inquire about depression symptoms in these patients so that they can be appropriately treated.  相似文献   
89.
BACKGROUND AND OBJECTIVES: To determine differences in the amount of work involved in caring for functionally monocular patients who undergo cataract surgery compared with binocularly sighted patients. PATIENTS AND METHODS: This was a retrospective study that included 100 consecutive functionally monocular patients and 100 binocularly sighted control patients matched by age (+/-5 years) and date of surgery ( +/-1 year). Office records were reviewed to determine several measures of office and operating room work effort. RESULTS: There was no difference between groups in preoperative telephone calls (P = .136), postoperative telephone calls (P = .580), preoperative office visits (P = .875), postoperative office visits (P = .601), or the number of times surgery was scheduled (P = 1.00). Monocular patients required more time for surgery (37.4 minutes) than binocular patients (32.4 minutes) (P= .010). CONCLUSIONS: It takes longer to perform cataract surgery on functionally monocular patients than on binocularly sighted patients.  相似文献   
90.
B M Bowman  S C Miller 《BONE》1986,7(5):351-357
The purpose of this study was to determine the capacity of the bone-lining cell, which covers most nonremodeling bone surfaces in the adult skeleton, to proliferate and contribute to the rapid endosteal osteogenic response following estrogen treatment in male Japanese quail. In control, untreated birds bone-lining cells cover most of the femoral endosteal surface. Bone-lining cells are thinly extended along bone surfaces, have flat nuclei, and account for about 77% of the cells adjacent to the bone surface. The lineal density of bone surface cells in the controls was about 21 cells/mm of bone surface. By 16-20 h after estrogen administration cells with larger, round nuclei were seen on the bone surface and some of these cells contained a 3H-thymidine (3H-TdR) label. Within the first 24 h after estrogen administration the lineal bone surface cell density had increased to about 38 cells/mm. At 20-30 h after estrogen administration, most of the cells adjacent to the bone surface were round. The peak 3H-TdR labeling of cells immediately adjacent to the bone surface occurred about 36 h after estrogen administration. By 48 h the bone surface was covered with osteogenic cells and developing medullary bone. These results suggest that the bone-lining cell in the adult appears to retain some proliferative capability and osteogenic potential. However, because a rapid increase in cell density began prior to the rapid increases in 3H-TdR labeling, as well as the appearance of mitotic figures on the bone surface, another source of cells may have also contributed to the osteogenic response induced by estrogen.  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