全文获取类型
收费全文 | 14915篇 |
免费 | 973篇 |
国内免费 | 65篇 |
专业分类
耳鼻咽喉 | 137篇 |
儿科学 | 588篇 |
妇产科学 | 254篇 |
基础医学 | 1688篇 |
口腔科学 | 447篇 |
临床医学 | 1083篇 |
内科学 | 3414篇 |
皮肤病学 | 304篇 |
神经病学 | 742篇 |
特种医学 | 541篇 |
外科学 | 2129篇 |
综合类 | 259篇 |
一般理论 | 7篇 |
预防医学 | 847篇 |
眼科学 | 654篇 |
药学 | 1503篇 |
中国医学 | 95篇 |
肿瘤学 | 1261篇 |
出版年
2023年 | 85篇 |
2022年 | 222篇 |
2021年 | 439篇 |
2020年 | 248篇 |
2019年 | 320篇 |
2018年 | 409篇 |
2017年 | 276篇 |
2016年 | 321篇 |
2015年 | 396篇 |
2014年 | 537篇 |
2013年 | 666篇 |
2012年 | 968篇 |
2011年 | 1043篇 |
2010年 | 533篇 |
2009年 | 492篇 |
2008年 | 766篇 |
2007年 | 779篇 |
2006年 | 753篇 |
2005年 | 662篇 |
2004年 | 634篇 |
2003年 | 569篇 |
2002年 | 547篇 |
2001年 | 349篇 |
2000年 | 352篇 |
1999年 | 276篇 |
1998年 | 139篇 |
1997年 | 94篇 |
1996年 | 90篇 |
1995年 | 95篇 |
1993年 | 74篇 |
1992年 | 191篇 |
1991年 | 201篇 |
1990年 | 193篇 |
1989年 | 167篇 |
1988年 | 162篇 |
1987年 | 192篇 |
1986年 | 157篇 |
1985年 | 122篇 |
1984年 | 148篇 |
1983年 | 98篇 |
1982年 | 72篇 |
1980年 | 69篇 |
1979年 | 87篇 |
1977年 | 65篇 |
1976年 | 67篇 |
1975年 | 68篇 |
1974年 | 91篇 |
1973年 | 77篇 |
1972年 | 66篇 |
1971年 | 59篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
A K Rama Krishna Shivanand Patil Grs Srinivas Rao Ajit Kumar 《Indian journal of gastroenterology》2006,25(2):97-98
Gastrointestinal manifestations of dengue fever are mainly in the form of bleeding or liver function abnormalities. Dengue fever presenting as acute colitis-like picture is not reported to date. We report a 50-year-old man with dengue fever presenting with lower gastrointestinal bleeding and colonoscopic features of acute inflammatory colitis. 相似文献
42.
M S Rao M M Mangino M I Usman V Subbarao D G Scarpelli M K Reddy J K Reddy 《Cancer research》1987,47(6):1657-1662
In this study we have investigated the effect of a single dose of tannic acid, administered s.c., on the nucleolar ultrastructure of hepatocytes transplanted into a syngeneic or xenogeneic host in order to evaluate the validity of our hepatocyte transplantation system as an in vivo alternative to the use of whole animals to test for species and strain differences to the effects of hepatotoxins. Within 4-6 h following tannic acid injection, rat hepatocytes transplanted into the anterior chamber of eye and inguinal fat pads of rat and athymic nude mouse, showed changes of nucleolar components, with separation of ribonucleoprotein containing granules into discrete dark zones. These dark areas were surrounded by light areas consisting of granular and fibrillar components of the nucleolus. These changes were identical to tannic acid-induced nucleolar alterations in the homotopic liver. Hamster and rat hepatocytes xenotransplanted into athymic nude mice also displayed prominent nucleolar alterations in response to tannic acid. The similarity and extent of nucleolar alterations observed in transplanted hepatocytes and the in situ homotopic liver cells attest to the usefulness of the hepatocyte transplantation system for the evaluation of species differences in biological response to toxic/carcinogenic effects of xenobiotics. 相似文献
43.
44.
C Sekar S Rajasekaran Rajesh Kannan Shashidhar Reddy T Ajoy Prasad Shetty Yogesh K Pithwa 《The spine journal》2004,4(3):261-264
BACKGROUND CONTEXT: Administration of analgesic medication, before the actual onset of painful stimulus, is more effective than that after the onset of painful stimulus. This is the principle of preemptive analgesia. Although it is often considered superior to other forms of analgesia, its role in postoperative pain relief after lumbosacral spinal surgery has not been fully investigated. PURPOSE: To analyze the efficacy of preemptive analgesia with a single caudal epidural injection for patients undergoing surgeries on the lumbosacral spine by the posterior approach. STUDY DESIGN/SETTING: Randomized, double-blinded and controlled clinical trial. PATIENT SAMPLE: Eighty-two patients who underwent discectomy in the lumbosacral spine by the posterior approach, with or without instrumentation, were randomized to the control group (n=40) and to the study group (n=42). METHODS: Patients in control group received a single caudal epidural injection of 20 ml of normal saline. Patients in study group received a single caudal epidural injection of 20 ml containing bupivacaine and tramadol as the active agents. The time interval between this injection and the surgical incision was never less than 20 minutes in either of the groups. This facilitated enough time for the drug to get fixed to the nerve roots, leading to effective preemptive analgesia. OUTCOME MEASURES: Patients were monitored for postoperative pain immediately after surgery when they had completely recovered and regained consciousness from general anesthesia, and subsequently 4, 8, 12 and 24 hours thereafter. Pain was quantified using the visual analog scale (VAS) and the verbal rating scale (VRS). The time at which supplemental analgesic medication was first demanded in the postoperative period by the patient was also noted. RESULTS: The two groups were comparable for age, sex, body weight and the type of surgery they underwent. Because the data did not have a normal Gaussian distribution, the one-tailed Mann-Whitney test, being a nonparametric test, was adopted for statistical analysis. Accordingly, VAS and VRS values at all time intervals were significantly lower (p<.0001) in the study group as compared with the control group. This indicated significantly better pain relief in the study group. There was also a significant delay (p=.0041) in the first demand for supplemental analgesic medication in the postoperative period in the study group. No complication specific to the procedure was noted except for the development of postoperative urinary retention, which was transient and appropriately managed with urinary catheterization. CONCLUSIONS: Preemptive analgesia with a single caudal epidural injection of bupivacaine and tramadol is a safe, simple and effective method for postoperative pain relief. 相似文献
45.
Previous work from this laboratory has already indicated that capsaicin, stabilizes the rat lung membrane lipid system on long-term treatment. This stabilization of the membrane is further supported by our present findings that capsaicin pretreatment causes significant inhibition of various chemically induced lipid peroxidative changes at both cellular and subcellular levels. Both in vivo and in vitro studies, using whole lung and liver tissue slices and mitochondrial and microsomal fractions, have shown that capsaicin pretreatment inhibits peroxidative changes at both cellular and subcellular levels. Both in vivo and in vitro studies, using whole lung and liver tissue slices and mitochondrial and microsomal fractions, have shown that capsaicin pretreatment inhibits peroxidative changes induced by different chemical irritants such as chloroform, dichloromethane, carbon tetrachloride as well as ferrous sulphate. 相似文献
46.
Ambakumar Nandakumar Narayanappa Anantha Thalagavadi Venugopal Sreerama Reddy Bapsy Padmanabhan Kumara Swamy Dinesh Doval Clementina Ramarao 《International journal of cancer. Journal international du cancer》1995,63(1):37-42
Lymphoid and haemopoietic malignancies as a group constitute one of the important cancers in India, as elsewhere in the world. While information on incidence and mortality of these cancers, and that on survival, are available from most developed countries, there are very few reports describing this experience in developing ones. Population-based cancer registration commenced in Bangalore, India, in January 1982, under the auspices of the Indian Council of Medical Research. This source provides fairly complete and reliable incidence data, but, in order to obtain mortality and survival information, active follow-up involving visits of homes of patients was undertaken. Between 1982 and 1989, 1397 cases of lymphoid and haemopoietic malignancies were registered in the Bangalore cancer registry, giving an age-adjusted incidence rate of 7.7 and 4.8 per 100,000 in males and females respectively. Active follow-up provided mortality/survival information in 1267 or 90.7% of these cases. The overall observed 5-year survival for these cancers combined (both sexes) was 26%, and relative survival 28.4%. The 5-year survival rate was lower in all the individual lymphomas and leukaemias as compared with similar reports from the developed countries. Survival in Hodgkin's disease was influenced by clinical stage and age at presentation. 相似文献
47.
The localization of Na,K-ATPase in the lens is quite controversial. We explored this problem through immunoelectron microscopic examination of rat and human lens. Unlike previously reported results, we have found that Na,K-ATPase is localized in the basal plasma membrane, but not in the lateral or apical plasma membrane of both rat and human lens epithelium. The lens fiber lacked immunoreaction. Localization of Na,K-ATPase was also investigated in the cultured human lens epithelium and in lentoid. Immunoreaction was detected in the apical (facing the media) plasma membrane of the lens epithelium cultured on the lens capsule, whereas the reaction was observable in both apical and basal plasma membrane of the lens epithelium cultured on the biopore membrane filters. Immunoreaction in lentoid was observed in the surface plasma membrane. These data indicate that the polarized distribution seen in the in situ lens epithelium changes when these cells are cultured, and that Na,K-ATPase in the cultured lens cells including lentoid is located in the plasma membrane which is in contact with the growth media. This change in polarity of Na,K-ATPase distribution in cultured epithelial cells may be dictated by the need to maintain ion homeostasis by extrusion of sodium ions across the cell membrane facing the media. 相似文献
48.
49.
50.
Previous work showed that GABAergic differentiation in developing chick retina depends on insulin and cell interactions. Here, we investigated whether it depended on cell signaling mediated by retina cognin, a 50 kDa cell recognition molecule. Cognin mediates cell adhesion in vitro and occurs on retinal neurons that become both GABAergic and cholinergic. We investigated two markers of GABAergic differentiation: glutamate decarboxylase (GAD) activity and high-affinity GABA uptake. Both increase during differentiation of retinal neurons in culture and can be easily measured. We blocked cognin-mediated cell signaling with cognin antibody and found a reduction of the developmental increase in GAD activity in cultures of retinal neurons from 7 and 11 day chick embryos. There was no reduction of high-affinity GABA uptake. This suggested that cognin-mediated signaling was necessary for the normal developmental increase in GAD but not for high-affinity GABA uptake. These results contrasted with our previous observations on cholinergic differentiation in cultured retinal neurons. We found that cognin antibody blocked the normal developmental increase in choline acetyltransferase (ChAT) only if the cells were exposed before embryonic day 7. Thus, while both GAD and ChAT activity appear to be controlled by cell signaling involving cognin, the periods of developmental sensitivity for the two differentiation markers are different. Antibodies to other adhesion molecules, Ng-CAM, and N-cadherin, did not similarly affect GAD activity. Antibodies to laminin at a 10-fold higher concentration inhibited GAD activity only in early embryonic retina. Tests for protein synthesis and “housekeeping” enzyme activity demonstrated that the cognin antibody effect was selective for neuronal differentiation pathways. Thus, GABAergic differentiation in developing retina is sensitive to cell signaling mediated in part by cognin. 相似文献