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   10124篇
  免费   542篇
  国内免费   78篇
耳鼻咽喉   116篇
儿科学   239篇
妇产科学   184篇
基础医学   1305篇
口腔科学   240篇
临床医学   1038篇
内科学   2418篇
皮肤病学   112篇
神经病学   1164篇
特种医学   353篇
外科学   1658篇
综合类   13篇
预防医学   292篇
眼科学   105篇
药学   609篇
中国医学   12篇
肿瘤学   886篇
  2024年   10篇
  2023年   54篇
  2022年   151篇
  2021年   217篇
  2020年   134篇
  2019年   180篇
  2018年   253篇
  2017年   210篇
  2016年   250篇
  2015年   235篇
  2014年   359篇
  2013年   496篇
  2012年   775篇
  2011年   709篇
  2010年   400篇
  2009年   387篇
  2008年   672篇
  2007年   641篇
  2006年   684篇
  2005年   660篇
  2004年   690篇
  2003年   601篇
  2002年   509篇
  2001年   103篇
  2000年   76篇
  1999年   90篇
  1998年   118篇
  1997年   87篇
  1996年   94篇
  1995年   82篇
  1994年   69篇
  1993年   73篇
  1992年   66篇
  1991年   66篇
  1990年   48篇
  1989年   53篇
  1988年   40篇
  1987年   36篇
  1986年   39篇
  1985年   31篇
  1984年   38篇
  1983年   29篇
  1982年   37篇
  1981年   33篇
  1980年   28篇
  1979年   16篇
  1978年   16篇
  1977年   12篇
  1975年   10篇
  1972年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Familial amyloidotic polyneuropathy (FAP) is an inherited disease characterized by an abnormal systemic deposition of a mutant protein called transthyretin (TTR) with elective involvement of the peripheral nervous system, but often determining cardiac, gastrointestinal, and urinary tract dysfunction. FAP commonly affects the liver and the heart until end-organs failure. Transthyretin amyloidosis is today an accepted indication for orthotopic liver transplantation (OLT). Combined heart and liver transplantation (CHLT) may be an attractive and rational treatment option when both organs are contemporary involved by this type of amyloidotic disease. Nowadays, surgical indications and techniques are far from being consolidated because only few cases of CHLT have been previously reported in literature. From November 1999 to May 2006, we performed five orthotopic combined heart and liver transplantations for FAP at our institution. Our surgical experience and clinical outcomes are herein reported.  相似文献   
23.
Using a corticostriatal slice preparation, we have recently shown that tetanic stimulation of the corticostriatal pathway produces long-term depression (LTD) of striatal excitatory synaptic transmission. In the present study we have analysed the relationship between LTD and the striatal release of different endogenous transmitters. Samples of perfusate were collected via a small cannula placed just above the surface of the striatal slice close to the recording electrode, and were analysed by HPLC. The high-frequency stimulation (100 Hz, three trains, 3 s duration, 20 s intervals) used to induce LTD caused a significant but transient increase in the release of both excitatory (aspartate and glutamate) and inhibitory (glycine and GABA) amino acid transmitters. Tetanic stimulation also produced a significant, but transient increase in the release of endogenous dopamine. We conclude that the tetanic stimulation of the corticostriatal pathway is able to induce a large but transient release of excitatory amino acids and of dopamine, whose participation in the induction of striatal LTD has been demonstrated previously. Moreover, the maintenance of this form of synaptic plasticity does not seem to require a sustained change in transmitter release.  相似文献   
24.
Purpose: To verify the efficacy of ultrasound (US)-guided injection of large amounts of ethanol into large or multiple liver lesions, in a single session under general anesthesia (one-shot PEI) for percutaneous ablation of hepatic tumors. Methods: Twenty-nine patients (27 with 51 hepatocellular carcinoma (HCC) nodules on cirrhosis, diameter range 1.0<+>–<+>9.0 cm; two patients with a single metastasis from the gastroenteric tract, 5.0 and 9.0 cm, respectively, in diameter) were treated with one-shot PEI. Results: The total volume of alcohol delivered per patient ranged from 16 to 210 ml. Mean ethanol volume in all patients was 49 ml. Dynamic computed tomography (CT) examination showed complete necrosis in 41 of 50 lesions. Two patients died of hypovolemic shock due to massive upper gastrointestinal bleeding, 3 and 7 days, respectively, after the interventional procedure. All the remaining patients are alive (follow-up 5<+>–<+>14 months) except one who died of liver failure 5 months after. New HCC nodules occurred in six patients within 6 months and one intralesional relapse was recorded. Conclusion: In this preliminary experience, one-shot PEI is as effective in inducing liver tumor necrosis as traditional PEI; its advantages are shorter treatment time and the capability of treating larger and multiple liver lesions.  相似文献   
25.
The authors review the latest theories of peripheral nerve regeneration and repair. They present their research on nerve regeneration including the alterations in the mother cell body, and in the distal part of the axon, and the time required to reach the best production of amino acids for cytoskeleton reconstruction. Other research of particular interest which is presented regards the chemotactic arrangement of motor and sensory axons inside a vein. This research has shown that the axons are able to find their way to the appropriate (sensory or motor) distal endoneural tubes.Adoption phenomena are also presented.The discussion of surgery includes the type (suture, glueing, grafts, tubulization) and the time of surgical repair. Timing and repair strategies are related to the site of the lesion (which can require that a greater or smaller amount of cytoskeleton be reconstructed), the type of the injury, the state of surrounding tissues, the age of the patients, injuries to muscles, tendons, bones, vessels and skin. A scheme of strategy is proposed.  相似文献   
26.
Summary Serum digoxin and beta-methyldigoxin (BMD) were measured in 165 elderly patients (age >60 years) admitted to hospital, of whom 109 had been treated at home with digoxin and 56 with BMD.The mean BMD level was significantly lower than that of digoxin (1.1 vs. 1.4 ng/ml). Creatinine clearance and daily dose were the variables most strongly associated with digoxin level, and the prescribed dose and serum albumin were the best predictors of the BMD concentration. Compliance was assessed by a compliance index (CI), namely the ratio of the measured glycoside concentration, corrected for creatinine clearance, over the expected steady-state dose, calculated from a hospitalized reference group. Compliant individuals in both treatment groups, i.e. those with a CI > the median value, were characterized by a lower daily dose and dosage frequency.Toxicity, whether clinical or electrocardiographic, was present in 9% of the patients and was associated only with a significantly higher mean serum level of the drug.  相似文献   
27.
Circumferential choledochoplasties with vascular grafts have rarely been attempted either experimentally or in clinical practice. In this study, choledochoplasties using autologous venous and arterial grafts were performed in rats. Sixty-four rats were randomly selected into five treatment groups: A) venous interpositional graft replacement of a choledochus gap without a stent; B) venous graft with prolene stent; C) venous graft with polyethylene stent; D) arterial graft; E) a control group with simple resection between ligatures in the choledochus. The operative mortality in treatment groups B, C, D, and E, was 0, and 13% in group A. At 12 weeks follow-up, all the rats in group E had died, whereas, 52.2% (P <.05) of the rats in group A, 30% of the rats in group B, 57% of the rats in group C, and 92.8% of the rats in group D survived treatment. Surviving animals were sacrificed at 3 months for further examination. The morphology and caliber of the common bile duct of these rats were normal in 25% of the rats in group A, 33% of the rats in group B, 25% of the rats in group C, and 84.6% of the rats in group D. Proximal dilations were found in the rats presenting with abnormal morphology. The dilations were less marked in the group treated by arterial choledochoplasties. Laboratory and clinical cholestatic parameters were within normal ranges in the presence of common bile duct dilations less than four times the normal duct caliber. Electron microscopic examination of the venous and arterial graft at 3 months follow-up revealed a fibrous ring composed of collagen fibers, fibroblasts, and remnants of elastic fibers. Regenerated ductal epithelium encompassed both types of grafts. Epithelialization was more pronounced in venous grafts as compared to arterial grafts. Biliary epithelium was able to colonize the venous grafts and resume cell specialization and function as in normal biliary epithelium. The most satisfactory results were obtained using venous grafts with stents or by using arterial grafts. © 1993 Wiley-Liss Inc.  相似文献   
28.
29.
Pain in individuals with RASopathies is a neglected topic in literature. In this article, we assessed prevalence and profile of pain in a sample of 80 individuals affected by RASopathies. The study sample included individuals with Noonan syndrome (N = 42), Costello syndrome (N = 17), and cardio‐facio‐cutaneous syndrome (N = 21). A set of standardized questionnaires and scales were administered (VAS/numeric scale, r‐FLACC, Wang‐Baker scale, NPSI, BPI, NCCPC‐R) to detect and characterize acute and chronic pain and to study the influence of pain on quality of life (PEDs‐QL, SF‐36) and sleeping patterns (SDSC); revision of past medical history and multisystemic evaluation was provided. Available clinical data were correlated to the presence of pain. High prevalence of acute (44%) and chronic (61%) pain was documented in the examined sample. Due to age and intellectual disability, acute pain was localized in 18/35 individuals and chronic pain in 33/49. Muscle‐skeletal and abdominal pain was more frequently reported. The intensity of acute and chronic pain interfered with daily activities in 1/3 of the sample. Pain negatively impacted on QoL and sleeping patterns. This work documents that pain is highly prevalent in RASopathies. Future studies including subjective and objective measures of pain are required to discriminate a somatosensory abnormality from an abnormal elaboration of painful stimuli at a central level.  相似文献   
30.
Isothiocyanates (ITCs) are commonly found in cruciferous vegetables. A variety of biological activities have been ascribed to ITCs, such as inhibition of cytochrome P450 enzymes and induction of phase II enzymes in animal models. ITCs are also able to block cell-cycle progression and induce apoptosis in human cancer cells in vitro. In this study, we evaluated the ability of the ITC sulforaphane to protect cultured human lymphocytes from micronucleus (MN) induction by four different mutagens: ethyl methanesulfonate (EMS), vincristrine (VIN), H(2)O(2) and mitomycin C (MMC). To understand the mechanisms of action of sulforaphane, the cultures were treated with the compound before, during and after treatment with the mutagens; in addition, the cultures were evaluated for the induction of apoptosis. Up to 10 microM, sulforaphane was non-genotoxic by itself, while 30 microM sulforaphane reduced the replicative index of the cells by more than 60%. Moreover, 1-10 microM sulforaphane reduced the MN frequency induced by EMS, VIN, H(2)O(2) and MMC in at least one of the treatment protocols; it had no effect on H(2)O(2)-MN induction in the post-treatment protocol, and it increased MN induction by MMC in the pre-treatment protocol. Apoptosis was produced in the cultures treated with sulforaphane alone. The fraction of apoptotic cells was increased after co- or post-treatment with sulforaphane and EMS and MMC, suggesting that sulforaphane-mediated apoptosis may remove highly damaged cells induced by these agents. Other mechanisms are involved in the anti-genotoxic activity of sulforaphane against VIN and H(2)O(2). Taken together, our findings indicate that under certain conditions sulforaphane possesses anti-genotoxic activity in vitro and that further studies are warranted to characterize this property in vivo.  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