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   309450篇
  免费   23366篇
  国内免费   5120篇
耳鼻咽喉   4700篇
儿科学   9963篇
妇产科学   5469篇
基础医学   25420篇
口腔科学   9630篇
临床医学   27209篇
内科学   43613篇
皮肤病学   5371篇
神经病学   17405篇
特种医学   10171篇
外国民族医学   11篇
外科学   43093篇
综合类   35658篇
现状与发展   10篇
一般理论   30篇
预防医学   32981篇
眼科学   3962篇
药学   24540篇
  336篇
中国医学   26483篇
肿瘤学   11881篇
  2023年   7010篇
  2022年   10718篇
  2021年   15089篇
  2020年   13750篇
  2019年   19961篇
  2018年   16839篇
  2017年   12284篇
  2016年   9070篇
  2015年   9111篇
  2014年   16864篇
  2013年   16113篇
  2012年   13812篇
  2011年   17949篇
  2010年   12380篇
  2009年   11218篇
  2008年   10667篇
  2007年   10232篇
  2006年   8761篇
  2005年   7953篇
  2004年   6928篇
  2003年   5884篇
  2002年   5318篇
  2001年   5054篇
  2000年   5684篇
  1999年   5518篇
  1998年   4845篇
  1997年   3692篇
  1996年   2710篇
  1995年   2237篇
  1994年   2144篇
  1993年   1694篇
  1992年   1652篇
  1991年   1434篇
  1990年   1366篇
  1989年   1144篇
  1988年   1137篇
  1987年   883篇
  1985年   3778篇
  1984年   5090篇
  1983年   3680篇
  1982年   4035篇
  1981年   3429篇
  1980年   3023篇
  1979年   2779篇
  1978年   2294篇
  1977年   1926篇
  1976年   2157篇
  1975年   1729篇
  1974年   1496篇
  1973年   1434篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Zusammenfassung. Der Hundebandwurm, Echinococcus, kann in seinem Larvenstadium alle Teile des menschlichen K?rpers, zumeist die Leber, als Zwischenwirt befallen. Der prim?re Knochenbefall ist mit weniger als 2 % aller Echinococcusl?sionen sehr selten. Wir berichten über einen Fall eines ausgedehnten linksseitigen Becken- und Femurbefalls. Die Destruktion des Hüftgelenks, des Os pubis sowie der ausgedehnte Befall des Os ileum und des proximalen Femurs machten eine Hüftgelenk- und Beckenteilresektion sowie den prothetischen Ersatz notwendig. Ein Rezidiv im Bereich der linken Leiste nach 5 Jahren, ausgehend vom proximalen Femur, wurde mit erneuter Resektion und Hüftprothesenwechsel behandelt. Der prim?r eingebrachte Polyacetal-Beckenersatz mu?te dabei wegen Instabilit?t ebenfalls ausgetauscht werden. Ein sonderangefertigter CAD-Beckenersatz (CAD = „computer-aided designed“) wurde implantiert. Additiv wurde eine Chemotherapie mit Mebendazol durchgeführt. Die Radikalit?t der Resektion beim oss?ren Echinococcusbefall wird diskutiert.   相似文献   
992.
Summary. The so-called extended diagnostic laparoscopy (EDL) facilitates the comprehensive exploration of the abdominal cavity, thus improving the precision of the pretherapeutic tumor staging in gastrointestinal malignancies. EDL comprises visual inspection with a specific preparation of all relevant sites, laparoscopic sonography and retrieval of samples for biopsy and cytology. Additional relevant therapeutic information was obtained through EDL in 40.5 % of gastric cancer patients. EDL could be of similar importance for diagnosing esophageal, hepatobiliary and pancreatic malignancies.   相似文献   
993.
994.
Solid customized and prefabricated silicone implants have been used by the author for 15 years in a wide range of chest wall deformities. Chest wall implants are often used in males seeking to augment a muscularly deficient or underdeveloped chest; however, their greatest use has come in a variety of deformities both congenital and acquired, such as pectus excavatum, Poland's Syndrome, and pectoralis muscle tears. The implants can be either customized using a moulage technique or are prefabricated, manufactured implants which can be modified on the operating table to repair the contour deformity. The immediate postoperative problem of seroma and subcutaneous implant ``show' has been minimized by careful planning, gentle technique, deep insertion, improved patient positioning on the operating room table, and the use of oral anti-inflammatory medications. The long-term results of these implants seem very satisfactory. The patients are usualy physically active, and the implants show no long-term sequelae such as seroma, infection, displacement, or rupture.  相似文献   
995.
In this study, skin-infiltrating cells were characterized in both the active and remission phases of post-burn hypertrophic scar biopstes. Immunohistochemistry examination of active phase samples showed an abundant presence of Langerhans cells, T cells, macrophages, a low presence of natural killer cells and the lack of B lymphocytes. In active hypertrophic scars T lymphocytes infiltrate deep into the superficial dermis and are also observed in the epidermis: CD3+ cells were present at about 222±107 per 0.25 mm2. In particular the analysis of lymphocyte subpopulations showed that CD4+ T cells predominate in the dermis as well as in the epidermis of active hypertrophic scars whereas CD8+ cells were less well represented (CD4/CD8 ratio is 2.06). This distribution was also shown in remission phase samples and in normotrophic scar specimens, although the lymphocyte number was significantly lower. Approximately 70 per cent of T lymphocytes present in the tissue involved in active phase hypertrophic scar samples were activated (positive with anti-HLA-DR and IL-2 receptor antibodies) which is significantly higher than remission phase hypertrophic and normotrophic scars, in which positivity was 40 and 38 per cent, respectively. Upon activation, the lesional lymphocytes release several cytokines, locally and transiently, that interact with specific receptors in response to different stimulation. Central to the immune hypothesis of hypertrophic scars is that some of the T-cell lymphokines act on keratinocytes, fibroblasts and other cell types to induce changes characteristic of these scars. The presence and close proximity of activated T lymphocytes and antigen-presenting cells of various phenotypes in both the epidermis and dermis of hypertrophic tissues provides strong circumstantial evidence of a local immune response. However, the manner in which T cells achieve and maintain their activated state in hypertrophic tissues in not yet known, and both antigen-dependent and independent mechanisms may contribute.  相似文献   
996.
During the past 20 years, numerous techniques have been described to improve the results of facelifting as well as the duration of its rejuvenating effect. These increasingly aggressive techniques have increased the operating time, the potential morbidity of the operation, and the duration of convalescence. No one can ensure that this evolution in sophistication of rhytidectomy techniques give longer lasting results. Therefore, a simple technique applied under the appropriate indications gives good and predictable results.  相似文献   
997.
Agents for prevention or treatment of osteoporosis must now be tested in a large animal species that exhibits bone remodeling. Ovariectomized, nonhuman primates provide one such model, and they consistently develop osteopenia accompanied by high bone turnover rates. The goal of this study was to further characterize this model, and particularly to determine the effect of ovariectomy on bone strength in vertebrae and femoral necks. Longitudinal evaluations of spinal bone mass and serum markers of bone turnover were performed in 19 sham-ovariectomized (SHAM) and 18 ovariectomized (OVX), domestically reared cynomolgus monkeys, aged >9 years. OVX monkeys lost bone relative to both baseline values and SHAM controls. Serum markers of bone turnover were increased by OVX. After 72 weeks, both vertebral bone compressive strength and femoral neck breaking strength were significantly decreased in OVX animals compared with SHAM. Ovariectomized cynomolgus monkeys, like postmenopausal women, develop accelerated bone loss, increased bone turnover, and reduced bone strength, and provide a suitable large animal model for efficacy studies with agents for prevention or treatment of osteoporosis. Received: 24 June 1996 / Accepted: 3 September 1996  相似文献   
998.
Urinary excretion of cross-linked N-telopeptide of type I collagen (NTx) has been reported to be a specific marker of bone resorption [18]. We assessed a new immunoassay for NTx as an indicator of changes in bone resorption caused by spontaneous menopause and compared cross-sectionally the levels of urinary NTx, hydroxylysylpyridinoline (HP), lysylpyridinoline (LP), hydroxyproline (OH-Pr), other serum biochemical indices, and lumbar spine and proximal femur bone mineral density (BMD). Eighty-one Japanese women aged 22–77 participated in this study; 36 were premenopausal and 45 were postmenopausal. Urinary HP, LP, and NTx stayed at low levels in the premenopausal period and rose 21%, 30%, and 67% in the postmenopausal period, respectively. The rise in LP and NTx was statistically significant (P < 0.01), suggesting that NTx is mostly released from bone matrix when bone resorption is accelerated. When premenopausal women were divided into two age groups and postmenopausal women were divided into two groups according to years since menopause (YSM) there were significant differences in LP and NTx between women <4 YSM and women aged <40 and those women aged 41+ (P < 0.01 and P < 0.05, respectively). A significant 110% increase in urinary NTx and a 48% increase in urinary LP were observed in postmenopausal women compared with age-matched premenopausal women aged 45–55. All biochemical markers other than serum PTH correlated significantly with each other (r = 0.243–0.858, P < 0.05–0.0001). Urinary NTx inversely correlated with lumbar spine BMD. When postmenopausal women were divided into three groups, the correlation between bone resorption and formation markers in women 0-1 YSM was greater than in women 2–10 YSM and in women 11 + YSM, indicating that resorption and formation are coupled at the early postmenopausal period. We conclude that urinary NTx is responsive to changes in bone metabolism caused by estrogen deficiency and may be a more sensitive and specific marker than HP, LP, or OH-Pr in the early postmenopausal years. Received: 15 February 1995 / Accepted: 18 October 1996  相似文献   
999.
The purpose of this study was to estimate the radiation doses to nursing staff, other patients, accompanying persons and family members deriving from patients undergoing 111In-DTPA-d-Phe-1-octreotide (111In-OCT) scintigraphy. Dose rates were measured from 16 patients who had received an intravenous injection of 140±40 MBq 111In-OCT. The measurements were performed at three different distances (0.5, 1 and 2 m) at 10–20 min, 5–7 h and 24 h (and in some cases, up to 48 h) after administration of 111In-OCT. The effective half-lives of the biexponential decrease of the dose rates were estimated to be 2.94±0.27 h (T 1) and 65.17±0.58 h (T 2). The calculated maximum dose to other persons in the waiting area was 27.2 μSv, to family members 61.5 μSv, to nursing staff in a ward 24.1 μSv and to neighbouring patients in the ward 69.5 μSv. Our results clearly demonstrate that the calculated maximum radiation exposure to accompanying persons, personnel, family members and other patients is well below the maximum annual dose limit for non-professionally exposed persons. Received 20 May and in revised form 9 July 1997  相似文献   
1000.
96名镍作业工人测定结果:非特异酯酶阳性细胞百分率(ANAE+%)为76.8%±8.0%,T细胞亚群CD2、CD4、CD8阳性细胞百分率(CD+2%、CD+4%、CD+8%)及CD+4/CD+8比值分别为65.6%±10.5%、56.3%±12.1%、34.3%±8.2%和1.76±0.6;酵母多糖刺激的外周血多形核白细胞化学发光(PMN-CL)本底和峰值分别为48±23和3073±684CPS/106PMN;血清硒和丙二醛含量分别为1.22±0.23和4.76±0.88μmol/L。与非镍作业的地区对照组比较,T细胞CD+8%增高,CD+4/CD+8比值下降,化学发光的本底值降低,峰值增加,血清Se含量下降,丙二醛含量升高。分析镍作业工人工龄与后三项指标变化的关系,工龄大于20年与小于10年有统计学上明显差别。这些观察指标为镍作业人员医学观察增加新的监护指标提供依据。  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