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   18051篇
  免费   999篇
  国内免费   107篇
耳鼻咽喉   119篇
儿科学   552篇
妇产科学   364篇
基础医学   2451篇
口腔科学   324篇
临床医学   1448篇
内科学   4426篇
皮肤病学   350篇
神经病学   1950篇
特种医学   860篇
外科学   2085篇
综合类   37篇
一般理论   2篇
预防医学   864篇
眼科学   168篇
药学   1286篇
中国医学   41篇
肿瘤学   1830篇
  2023年   151篇
  2022年   332篇
  2021年   542篇
  2020年   342篇
  2019年   449篇
  2018年   473篇
  2017年   352篇
  2016年   425篇
  2015年   450篇
  2014年   610篇
  2013年   803篇
  2012年   1140篇
  2011年   1204篇
  2010年   635篇
  2009年   588篇
  2008年   988篇
  2007年   1004篇
  2006年   898篇
  2005年   809篇
  2004年   761篇
  2003年   684篇
  2002年   646篇
  2001年   423篇
  2000年   421篇
  1999年   432篇
  1998年   167篇
  1997年   117篇
  1996年   120篇
  1995年   95篇
  1994年   92篇
  1993年   86篇
  1992年   278篇
  1991年   259篇
  1990年   265篇
  1989年   249篇
  1988年   188篇
  1987年   164篇
  1986年   183篇
  1985年   207篇
  1984年   120篇
  1983年   100篇
  1982年   67篇
  1981年   48篇
  1979年   108篇
  1977年   56篇
  1976年   53篇
  1975年   53篇
  1974年   47篇
  1973年   56篇
  1971年   47篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Surgical treatment of rectal cancer is still controversial as regards the type of operation and the extent of lymphadenectomy. Four hundred and fifty-eight patients with rectal cancer operated on at two different hospitals (206 patients, Surgical Department, S. Martino General Hospital and 252 patients, Surgical Department, Galliera General Hospital) in the decade 1980-1989 were studied. None of the patients were submitted to adjuvant or neoadjuvant therapy. The operations opted for were anterior resection for carcinoma of the upper rectum, anterior resection or abdominoperineal resection for carcinoma of the middle rectum, and abdominoperineal resection for lower rectal cancer. At the S. Martino General Hospital, anterior resection comprised ligation of the inferior mesenteric artery at its origin, with subsequent preaortic lymphadenectomy. In abdominoperineal resection, the pelvis was left open and was closed later. At the Galliera General Hospital, preaortic lymph node dissection was not performed, and abdominoperineal resection comprised a one-stage pelvic floor closure. Survival was no different in the two patient populations. Extended lymphadenectomy was of no benefit in terms of survival in operated rectal cancer patients. Abdominoperineal resection may still be useful for selected patients.  相似文献   
992.
OBJECTIVE: Radical surgical treatment improves the prognosis of patients affected by Inferior Vena Cava (IVC) thrombosis concomitant to renal carcinoma. However, thrombus extension above the infrahepatic IVC represents a major technical topic for surgeons because of the possible occurrence of uncontrollable haemorrhages and tumor fragmentation. We report the results of an innovative surgical approach to caval thrombosis including the isolation of the IVC from the liver as routinely performed during liver harvesting. In the presence of retro-hepatic IVC thrombosis, this technique improves vascular control and allows to perform a large cavotomy with an en-bloc removal of the thrombus and the tumor. METHODS: From January 1995 through June 2003, 15 patients with renal cancer and caval thrombosis were treated at our Institution. Four, ten and one patients were respectively affected by an infrahepatic (Level I), retro-hepatic (Level II) and atrial (Level III) IVC thrombosis. RESULTS: All patients underwent radical surgical treatment. In presence of Level II caval thrombosis, the patients underwent the above reported surgical technique. Perioperative mortality was absent; major morbidity occurred in one patient (6.7%). The thrombus was radically removed in all cases. After a mean follow-up of 53.9 months (5-100 months) all patients but one are still alive. One patient died 9 months after surgery with multiple bilateral pulmonary metastases. CONCLUSIONS: Isolation of the retro-hepatic IVC is a safe and effective manoeuvre to significantly reduce perioperative mortality and morbidity in patients affected by Level II caval thrombosis concomitant to renal carcinoma.  相似文献   
993.
Sepsis may be defined as a clinical syndrome caused by an organism's response to infection. The complex alterations triggered by the infection include inflammation and systemic coagulopathy in the absence of effective fibrinolysis. Possible manifestations vary in entity and severity, ranging from systemic inflammatory response syndrome (SIRS) to septic shock and multiorgan dysfunction syndrome (MODS). The nurse can play a fundamental role in the timely recognition of SIRS and in the early identification of the onset of signs of organ damage. In this way, an additional aid to establishing diagnosis can be provided and targeted treatment instituted. Following a brief presentation of the pathophysiology and epidemiology of sepsis, the manifestations and attendant risks are described, the most appropriate monitoring methods and the main nursing tasks in treating sepsis are discussed. We present the results of our experience in identifying patients with sepsis through the application of selection criteria adopted from clinical studies on the use of activated protein C.  相似文献   
994.
This longitudinal study evaluated the effects of a triathlon season on bone metabolism and hormonal status. Seven male competitive triathletes (mean age 19.3 years, range 18 - 20) with 5.0 +/- 0.3 years of competition experience were tested twice during the season: at the beginning of training and 32 weeks later. Total and regional bone mineral density (BMD) was determined by dual-energy X-ray absorptiometry, while bone turnover was evaluated by specific biochemical markers: bone-specific alkaline phosphatase (B-ALP), osteocalcin, and urinary type I collagen C-telopeptide. In addition, sexual, calciotropic and somatotropic hormones were also analyzed. After 32 weeks, a BMD increase was found at the lumbar spine (1.9 %; p = 0.031) and skull (3.1 %; p = 0.048), while no variation was observed for total body or at the proximal femur. The B-ALP level decreased (-23.2 %; p = 0.031), but no variation was found for the other bone markers. 1.25 (OH) (2)D3, IGF-1 and the bioavailability IGF-1 index (IGF-1/IGFBP-3) increased by 18.3 % (p = 0.047), 29 % (p = 0.048), 33 % (p = 0.011), respectively, while PTH, testosterone, IGFBP-3 and cortisol concentrations were unchanged. In conclusion, the triathlon season had a moderately favourable effect on BMD, although a slowing down of bone formation activity was observed. No variation in hormonal levels was observed that could have limited the effects of exercise on bone tissue.  相似文献   
995.
Congestive heart failure (CHF) represents an enormous clinical problem and remains a leading cause of death despite advances in treatment. New treatments significantly impact mortality and disease course; they do not cure the underlying pathology. Gene transfer, the ability to genetically reprogram the heart in relevant cardiovascular disease models, allows testing the role of specific molecular pathways in disease pathogenesis. Potential therapeutic intervention targets can be then identified and approached with the full spectrum of therapeutic options, including traditional pharmacology, targeted synthesis of small molecule agonists or antagonists, biological agents (cells, antibodies, genetic material), or gene-based therapy. Lessons gleaned from gene transfer experiments on local modulation of cardiac genetic programs will guide attempts to transform early investigations into established therapy.  相似文献   
996.
997.
This study compares the fixed-bearing PFC Sigma Total Knee Arthroplasty to the recently introduced rotating-platform version of the same design in 26 patients. At an average follow-up time of 46 months for the fixed-bearing side and 16 months for the rotating-platform side, no significant differences were found in terms of knee preference, knee pain, range of motion, overall satisfaction, or Knee Society scores (KSSs). No revisions, subluxations, dislocations, or infections were seen. Also no radiographic evidence of component loosening, osteolysis, or malalignment was found in any knee. The results of cementing the PFC Sigma rotating-platform, posterior-stabilized total knee show excellent patient satisfaction at 1 year and comparable clinical and radiographic results to the fixed-bearing version.  相似文献   
998.
In eukaryotes, FK506-binding proteins with a molecular weight of 12 kDa (FKBP12s) influence a variety of signal transduction pathways that regulate cell division, differentiation, and ion homeostasis. Amongst these, TGFbeta signaling and calcineurin (CN) phosphatase activity is modulated by FKBP12 via binding to TGFbeta-family type I receptors (TbetaR-Is) or to the CN subunit A, respectively. In this work, we demonstrate the tissue-specific expression of the Schistosoma mansoni FKBP12 homologue (SmFKBP12) in the gonads of female parasites as well as in the tegument of both genders. Components of the TGFbeta pathway have been characterized in schistosomes and their roles in mediating host-parasite or male-female interactions proposed. We show that a schistosome TGFbeta-family type I receptor (SmTbetaR-I, SmRK-1) is expressed in the female gonads, suggesting that SmFKBP12 may regulate its activity in this tissue. This hypothesis is supported by yeast two-hybrid analyses showing a direct binding of SmFKBP12 and SmTbetaR-I, which was specifically inhibited by the drug FK506. Our data provide the first evidence for the activity of a transmembrane receptor in the vitellarium of schistosome females and indicate that FKBP12-meditated regulation of the TGFbeta pathway is evolutionarily conserved in a primitive metazoan such as Schistosoma. Furthermore, we show that the schistosome CN (SmCN) is not expressed in the female gonads, but co-localizes with SmFKBP12 only in the tegument. From these data we conclude an SmFKBP12/SmTbetaR-I, but not an SmCN/SmFKBP12 interplay in the female gonads.  相似文献   
999.
Brisinda G  Cadeddu F  Maria G 《The New England journal of medicine》2004,351(12):1259-60; author reply 1259-60
  相似文献   
1000.
Transplantation of neural progenitors or stem cells is a most useful tool to investigate the relative contribution of cell-autonomous mechanisms and environmental cues in the regulation of cell specification and differentiation during CNS development. To assess the capability of neocortical progenitor cells to integrate into foreign brain regions, here we examined the fate of precursor cells isolated from the dorsal telencephalon of E12 ss-actin-EGFP transgenic mouse embryos after heterotopic/heterochronic transplantation to the E16 rat brain in utero. Our observations show that donor cells were able to penetrate, survive and produce mature cell types into wide regions of the host CNS. Namely, EGFP-positive cells acquired site-specific neuronal identities in many telencephalic regions, including neocortex, hippocampus, olfactory bulb and corpus striatum. In contrast, incorporation into more caudal sites was much less efficient. A fraction of donor cells formed large aggregates that remained segregated from the host milieu. Such aggregates contained mature neurons and glia, including some EGFP-negative elements of host origin, and developed the complex organization of the mature nervous tissue. On the other hand, transplanted cells that engrafted in the parenchyma of extratelencephalic regions predominantly generated glial types. The few neurons failed to acquire obvious site-specific phenotypic traits and did not integrate into the local host architecture. Altogether, our observations indicate that E12 neocortical progenitors are already committed towards regional identities and are unable to modify their phenotypic choices when exposed to heterotopic environmental conditions along different rostro-caudal domains of the embryonic CNS.  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