全文获取类型
收费全文 | 518413篇 |
免费 | 38475篇 |
国内免费 | 16906篇 |
专业分类
耳鼻咽喉 | 6215篇 |
儿科学 | 13288篇 |
妇产科学 | 8444篇 |
基础医学 | 59567篇 |
口腔科学 | 13266篇 |
临床医学 | 50472篇 |
内科学 | 66530篇 |
皮肤病学 | 9077篇 |
神经病学 | 29974篇 |
特种医学 | 11747篇 |
外国民族医学 | 167篇 |
外科学 | 51478篇 |
综合类 | 79919篇 |
现状与发展 | 59篇 |
一般理论 | 29篇 |
预防医学 | 39691篇 |
眼科学 | 9161篇 |
药学 | 45255篇 |
406篇 | |
中国医学 | 36462篇 |
肿瘤学 | 42587篇 |
出版年
2024年 | 1505篇 |
2023年 | 7933篇 |
2022年 | 14091篇 |
2021年 | 19547篇 |
2020年 | 17887篇 |
2019年 | 23245篇 |
2018年 | 21255篇 |
2017年 | 18711篇 |
2016年 | 16560篇 |
2015年 | 16978篇 |
2014年 | 29954篇 |
2013年 | 32860篇 |
2012年 | 28191篇 |
2011年 | 30861篇 |
2010年 | 25352篇 |
2009年 | 23628篇 |
2008年 | 23871篇 |
2007年 | 24570篇 |
2006年 | 21899篇 |
2005年 | 19533篇 |
2004年 | 16600篇 |
2003年 | 14501篇 |
2002年 | 11715篇 |
2001年 | 10393篇 |
2000年 | 8545篇 |
1999年 | 7320篇 |
1998年 | 6378篇 |
1997年 | 5870篇 |
1996年 | 5098篇 |
1995年 | 4643篇 |
1994年 | 4260篇 |
1993年 | 3452篇 |
1992年 | 3201篇 |
1991年 | 2857篇 |
1990年 | 2404篇 |
1989年 | 2175篇 |
1988年 | 2050篇 |
1987年 | 1713篇 |
1986年 | 1605篇 |
1985年 | 4497篇 |
1984年 | 5423篇 |
1983年 | 3789篇 |
1982年 | 4256篇 |
1981年 | 3911篇 |
1980年 | 3465篇 |
1979年 | 3137篇 |
1978年 | 2690篇 |
1977年 | 2026篇 |
1976年 | 2239篇 |
1975年 | 1667篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Claudia Gedlicka Gudrun Hager Martina Weissenböck Wilhelm Gedlicka Birgit Knerer Johannes Kornfehl Michael Formanek 《Journal of oral pathology & medicine》2006,35(8):472-478
BACKGROUND: 1Alpha,25-dihydroxyvitamin D(3) [1,25(OH)(2) Vitamin D(3)] induces growth inhibition in squamous cell carcinoma (SCC) cell lines of the head and neck by arresting the cells in the G0/G1 phase of the cell cycle, probably due to an enhanced expression of p21, which could be demonstrated in other cell lines (JPPA, SCC9) before. In SCC25, a SCC cell line isolated from tongue, growth inhibition but no overexpression of p21 was detected. The retinoblastoma gene, as a direct target of G1 cyclin-CDK complexes, showed an obvious shift from the hyperphosphorylated to the hypophosphorylated form under 1,25(OH)(2)Vitamin D(3), which indicates that the growth inhibition takes place in the G0/G1 phase. To explore the possible pathway of growth inhibition in SCC25 we investigated other cell cycle inhibitors (p18, p19, p27). METHODS: Synchronized cells were treated with 1,25(OH)(2)Vitamin D(3) over 96 h. The cell cycle status and expression of cell cycle-regulating proteins was determined by fluorescence-activated cell sorting (FACS) and Western blotting. An overexpression of p18 in 1,25(OH)(2)Vitamin D(3) vs. ethanol-treated cells was determined until 30 h in SCC25. No influence was detectable on the expression of p27 and p19. CONCLUSION: One mechanism by which 1,25(OH)(2)Vitamin D(3) controls cell growth might be the upregulation of p21. As p21 was unsusceptible to 1,25(OH)(2)Vitamin D(3) in SCC25, other inhibiting proteins were necessary to be tested. The proven upregulation of p18 seems to be the responsible step for growth inhibition of 1,25(OH)(2)Vitamin D(3) in SCC25. 相似文献
72.
应用秩和比法研究门诊人数增长与门诊医疗质量因子的关系 总被引:3,自引:0,他引:3
目的研究医院门诊人数增长与门诊医疗质量因子的关系,找出影响门诊人数增长的主要门诊医疗质量因子。方法利用秩和比法对实例进行分析。结果影响门诊人数增长的门诊质量因子,首先是高中级职称比(χ2=32.43,P<0.05),其次是副高以上职称的坐诊工时比(χ2=31.91,P<0.05),再次是新技术项目或重大改革(χ2=28.54,P>0.05)。结论研究医院门诊人数增长与门诊医疗质量因子的关系时,秩和比法有应用推广的价值。 相似文献
73.
Anne-Catherine Bachoud-Lévi Philippe Hantraye Marc Peschanski 《Movement disorders》2002,17(3):439-444
Intrastriatal transplantation of striatal neuroblasts from human fetuses is a promising approach for treatment of Huntington's disease, on the basis of many experimental animal studies and, most recently, pilot clinical trials. Technically, several issues remain to be resolved (e.g., the precise site of dissection of the fetal tissue; the number and location of the fetal striatal implants; or the use of immunosuppressive therapy), and await larger-scale trials and purposely designed protocols. Further clinical data must also be obtained, and preliminary promising results must be replicated in a patient group large enough to provide conclusive results. It is important to establish (1) the amount of clinical benefit provided to the patient by the grafted cells; (2) the anticipated duration of clinical benefits; and (3) the secondary rate of decline after the benefit of the graft has been overbalanced. Evaluation of these parameters will require very long-term follow-up of the patients involved, over several years after grafting, before the technique can eventually be proposed widely to patients. 相似文献
74.
β-胡萝卜素立体异构体对环磷酰胺处理小鼠免疫功能的比较研究 总被引:3,自引:0,他引:3
就β-胡萝卜素立体异构体对环磷酰胺处理小鼠的免疫功能影响进行了比较研究。结果显示β-胡萝卜素立体异构体对外磷酰胺造成的免疫功能低下具有不同程度的改善作用,提高胸腺和脾脏指数,增强脾脏细胞对刀豆素A(ConA)的反应性和NK活性,血清溶菌酶含量也有所增加。综合各项指标,9-顺式和全反式混合物的作用最明显,提示一定浓度的9-顺式对于提高β-胡萝卜素对机体的总体作用是有一定意义的。 相似文献
75.
表皮生长因子对牛眼小梁细胞c—fos基因表达的诱导 总被引:4,自引:0,他引:4
目的研究表皮生长因子(epidermalgrowthfactor,EGF)对小梁细胞的作用。方法应用分子杂交技术研究EGF对体外培养的牛眼小梁细胞c-fos基因表达的诱导和3H胸腺核苷酸(3H-thymidineincorparation,3H-TdR)掺入法观察细胞DNA的合成。结果小梁细胞的3H-TdR掺入率随着EGF浓度不同而变化,浓度为20~150ng/ml时,细胞掺入率随浓度增加升高(P<0.01)。与对照组相比,EGF刺激停止生长的小梁细胞0.5小时后,c-fos基因开始表达,1小时后达高峰,至2小时后消失。不同浓度EGF刺激小梁细胞1小时后,c-fos基因表达呈浓度依赖性。结论实验结果表明EGF刺激小梁细胞增殖或进入生长状态,可能与c-fos基因产物的信号传递作用有关。 相似文献
76.
粉防己碱对野百合碱致大鼠肺动脉构形重建的逆转作用 总被引:2,自引:0,他引:2
以野百合碱复制Wistar大鼠肺动脉高压模型,用特殊染色方法观察粉防已碱对野百合碱致大鼠肺动脉构形重建的逆转作用,结果表明粉防已碱可选择性的降低野百合碱诱导的大鼠肺动脉高压的作用,并明显地逆转肺血管及肺组织损伤,降低肺动脉高压和右心室肥大,对体循环压力无影响 相似文献
77.
78.
The B cell functional response following ligation of surface(s) lgM is dependent upon the differentiation stage of the populationstudied: cross-linking slgM promotes proliferation of restingtonsillar follicular mantle (FM) B lymphocytes but induces apoptosisin the susceptible Epstein- Barr virus genome-negative Burkittlymphoma (BL) cell line Ramos (Ramos-BL). This study investigateswhether phosphatidylinositol-3-kinase (Pl3-kinase), which hasbeen reported to be intimately involved in the regulation ofcellular growth, plays a role in the regulation of these sig-promoted B cell responses, and uses the selective and irreversibleinhibitor of Pl3-kinase activity, wortmannin (Wm). In Ramos-BLB cells, at 8 h post-treatment, Wm triggers a transient increasein apoptosis of 16 ± 6.9% with a concomitant cellularloss of 16 ± 6.1% from the G1 phase of cell cycle; [3H]thymidineincorporation also decreases by 33 ± 5.0%, from 37,274c.p.m. ± 10% to 25,127 c.p.m. ± 4.0%. Moreover,at 72 h culture, Wm inhibits anti-lgM-induced FM B lymphocytelevels of [3H]thymidine incorporation typically by 47% and triggers80% apoptosis from the G0G1 phase of cell cycle. Ramos-BL Bcells exhibit high basal levels of Pl3-kinase activity, as determinedby immunoprecipitation with antibody to the p85 regulatory subunitof Pl3-kinase and 32P incorporation into phosphatidylinositol,which is not significantly affected by anti-lgM stimulation;by contrast, anti-lgM stimulates significant Pl3-kinase activityover negligible basal levels in FM B lymphocytes. Pre-treatmentwith Wm inhibits Pl3-kinase activity in both cell types. Takentogether these data indicate that in Ramos-BL B cells slgM-triggeredgrowth arrest and apoptosis is Pl3- kinase independent, whereasPl3-kinase activity is critical for slgM-triggered mitogenesisof FM B lymphocytes. Thus Pl3-kinase plays a pivotal role inthe regulation of both normal and neoplastic B lymphocyte progressionthrough the cell cycle, such that if this Pl3-kinase-dependentpathway is inhibited these cells default to apoptosis. 相似文献
79.
Sarah A. Taylor Jacqueline Benedetti David Schuller Stephen P. Richman Goronwy O. Broun Alexander Hantel 《Investigational new drugs》1993,11(2-3):227-229
Summary Twenty-two patients with recurrent or metastatic squamous cell carcinoma of the head and neck were treated with piroxantrone 150 mg/m2 intravenously every 21 days. There were no objective responses. The 95% upper confidence bound for response is 15%. Primary toxicity was hematologic. 相似文献
80.
Jay Magaziner Eleanor M. Simonsick T. Michael Kashner J. Richard Hebel 《Journal of clinical epidemiology》1988,41(11)
The present study evaluates the response comparability between 361 elderly hip fracture patients admitted from the community to seven Baltimore area hospitals between 1984 and 1986 and interviewer selected proxies on items pertaining to patients' pre-fracture health and functional status. Agreement across items ranges from very poor to good and varies with respect to the health or functional area assessed. Proxies tend to overestimate patient disability relative to the patients themselves, especially with regard to capacity to perform instrumental activities of daily living. Although proxies who report the greatest contact with patients respond most comparably to the patients, when they do disagree, proxies with the greatest patient contact tend to overestimate patient disability. The authors suggest that attention to item construction and phrasing may improve response comparability. 相似文献