全文获取类型
收费全文 | 6171篇 |
免费 | 339篇 |
国内免费 | 57篇 |
专业分类
耳鼻咽喉 | 28篇 |
儿科学 | 214篇 |
妇产科学 | 235篇 |
基础医学 | 640篇 |
口腔科学 | 75篇 |
临床医学 | 608篇 |
内科学 | 1255篇 |
皮肤病学 | 64篇 |
神经病学 | 687篇 |
特种医学 | 399篇 |
外科学 | 498篇 |
综合类 | 326篇 |
一般理论 | 4篇 |
预防医学 | 636篇 |
眼科学 | 64篇 |
药学 | 445篇 |
3篇 | |
中国医学 | 99篇 |
肿瘤学 | 287篇 |
出版年
2022年 | 43篇 |
2021年 | 78篇 |
2020年 | 64篇 |
2019年 | 75篇 |
2018年 | 103篇 |
2017年 | 111篇 |
2016年 | 105篇 |
2015年 | 123篇 |
2014年 | 146篇 |
2013年 | 238篇 |
2012年 | 333篇 |
2011年 | 325篇 |
2010年 | 202篇 |
2009年 | 214篇 |
2008年 | 329篇 |
2007年 | 310篇 |
2006年 | 304篇 |
2005年 | 301篇 |
2004年 | 239篇 |
2003年 | 228篇 |
2002年 | 175篇 |
2001年 | 194篇 |
2000年 | 180篇 |
1999年 | 132篇 |
1998年 | 78篇 |
1997年 | 82篇 |
1996年 | 89篇 |
1995年 | 76篇 |
1994年 | 69篇 |
1993年 | 71篇 |
1992年 | 94篇 |
1991年 | 91篇 |
1990年 | 93篇 |
1989年 | 97篇 |
1988年 | 100篇 |
1987年 | 81篇 |
1986年 | 63篇 |
1985年 | 86篇 |
1984年 | 67篇 |
1983年 | 39篇 |
1981年 | 26篇 |
1980年 | 26篇 |
1979年 | 30篇 |
1975年 | 33篇 |
1959年 | 41篇 |
1958年 | 66篇 |
1957年 | 75篇 |
1956年 | 73篇 |
1955年 | 83篇 |
1954年 | 51篇 |
排序方式: 共有6567条查询结果,搜索用时 475 毫秒
101.
外源核苷酸对免疫抑制小鼠胸腺细胞DNA损伤的影响 总被引:5,自引:0,他引:5
目的:检测外源核苷酸对经环磷酰胺诱导的免疫抑制小鼠胸腺细胞DNA损伤的影响。方法:采用18~20 g昆明种小鼠30只,雌雄各半,随机分成阴性对照组(NEC)、阳性对照组(POC)和核苷酸组(NTG),每组10只。NEC组和POC组小鼠均饲喂半纯合无核苷酸的基础日粮,NTG组则在基础日粮中添加0.25%的核苷酸,实验期为21 d。在实验结束前18 h POC组和NTG组小鼠按照150mg/kg bw的剂量腹腔注射环磷酰胺,NEC组注射生理盐水,实验结束时测定脾脏和胸腺脏器指数,并取胸腺细胞,做单细胞凝胶电泳,观察细胞DNA损伤情况。结果:在基础日粮中添加核苷酸对小鼠免疫器官重量没有显著影响(P>0.05),但能极显著降低受损胸腺细胞百分率(P<0.01)和受损细胞DNA尾长(P<0.01)。结论:外源核苷酸能显著降低免疫抑制小鼠受损胸腺细胞百分率和损伤程度。 相似文献
102.
自然流产妇女弓形虫感染的调查研究 总被引:2,自引:0,他引:2
目的 探讨自然流产妇女与弓形虫 (Tox)感染的相关性。方法 采用酶联免疫吸附试验(EL ISA)对自然流产的 4 76例孕妇外周血进行了弓形虫循环抗原 (CAg)和特异性抗体 (Tox- Ig M,Tox- Ig G)的检测 ,并和正常妊娠妇女作比较 ;应用聚合酶链反应 (PCR)技术对经 EL ISA测定为阳性的 1 4例孕妇流产物进行 Tox- DNA检测。结果 流产组 CAg,Tox- Ig M,Tox- Ig G等阳性率分别为 5 .2 5 % ,6 .30 % ,1 1 .76 % ,其中 CAg及 Tox- Ig M阳性率与正常孕妇相比 ,差异有非常显著性 (P<0 .0 1 ) ;1 4例流产物中 Tox- DNA阳性 8例 ,阳性率为 5 7.1 4 %。结论 Tox可通过胎盘传给胎儿 ,引起流产 ;孕妇急性感染与自然流产有相关性 ,CAg,Tox- Ig M,CAg+Tox- Ig M阳性率与发生流产次数呈正相关 相似文献
103.
目的探讨自我效能感与晕船症状的相关,以期寻找影响晕船的心理因素.方法对某院校参加海上实习的123名医疗本科学员用一般自我效能感量表、晕船自我效能感量表于出海作业前进行施测,用晕船症状评分量表于出海作业返回后进行评估.结果晕船自我效能感与晕船症状显著负相关(r=-0.470,P<0.01),而一般自我效能感量表与晕船症状的相关无统计学意义(r=-0.102,P>0.05).结论晕船自我效能感可能为个体发生晕船的心理影响因素之一. 相似文献
104.
Prognostic significance of tumor necrosis in ovarian cancer patients treated with neoadjuvant chemotherapy and interval surgical debulking 总被引:1,自引:0,他引:1
T. LE P. SHAHRIARI L. HOPKINS W. FAUGHT† & M. FUNG KEE FUNG 《International journal of gynecological cancer》2006,16(3):986-990
The objective of this study was to study the significance of tumor necrosis documented at the time of interval surgical debulking after neoadjuvant chemotherapy. Retrospective chart reviews were carried out from 1997 to 2005 to identify ovarian cancer patients treated with neoadjuvant chemotherapy. Patients' demographics together with disease characteristics, treatment-related variables, and outcomes were recorded. Cox proportional hazard models were built to model time to progression using predictor variables such as age, cancer stage, tumor grade, residual disease, percentage change in CA125 level from baseline, and degree of necrosis in resected tumor specimens. One hundred one patients were included in the study. Optimal debulking was achieved in 74% of the patients. Cox regressions revealed three significant predictive variables of time to first progression: younger age (hazard ratio [HR] = 0.95, 95% CI 0.92-0.98, P= 0.004), residual disease (P= 0.048), and the absence/minimal tumor necrosis after three cycles of neoadjuvant chemotherapy (HR = 1.97, 95% CI 1.01-3.87, P= 0.048). The estimated median survival was 50.66 months (95% CI 46.12-55.20). The lack of or minimal tumor necrosis after neoadjuvant chemotherapy is an independent risk factor for recurrent disease. 相似文献
105.
Corine C Visser Sanja Stevanovi? L Heleen Voorwinden Louis van Bloois Pieter J Gaillard Meindert Danhof Daan J A Crommelin Albertus G de Boer 《European journal of pharmaceutical sciences》2005,25(2-3):299-305
In this study, we aim to target pegylated liposomes loaded with horseradish peroxidase (HRP) and tagged with transferrin (Tf) to the BBB in vitro. Liposomes were prepared with the post-insertion technique: micelles of polyethylene glycol (PEG) and PEG-Tf were inserted into pre-formed liposomes containing HRP. Tf was measured indirectly by measuring iron via atomic absorption spectroscopy. All liposomes were around 100 nm in diameter, contained 5-13 microg HRP per mumol phospholipid and 63-74 Tf molecules per liposome (lipo Tf) or no Tf (lipo C). Brain capillary endothelial cells (BCEC) were incubated with liposomes at 4 degrees C (to determine binding) or at 37 degrees C (to determine association, i.e. binding+endocytosis) and the HRP activity, rather than the HRP amount was determined in cell lysates. Association of lipo Tf was two- to three-fold higher than association of lipo C. Surprisingly, the binding of lipo Tf at 4 degrees C was four-fold higher than the association of at 37 degrees C. Most likely this high binding and low endocytosis is explained by intracellular degradation of endocytosed HRP. In conclusion, we have shown targeting of liposomes loaded with protein or peptide drugs to the BCEC and more specifically to the lysosomes. This is an advantage for the treatment of lysosomal storage disease. However, drug targeting to other intracellular targets also results in intracellular degradation of the drug. Our experiments suggest that liposomes release some of their content within the BBB, making targeting of liposomes to the TfR on BCEC an attractive approach for brain drug delivery. 相似文献
106.
The quality of communication between parents and adolescent children in the case of parental cancer. 总被引:2,自引:0,他引:2
G A Huizinga A Visser W T A van der Graaf H J Hoekstra J E H M Hoekstra-Weebers 《Annals of oncology》2005,16(12):1956-1961
BACKGROUND: This study was designed to investigate: (i) parent-adolescent communication in families of cancer patients; (ii) relationships between parent-adolescent communication and posttraumatic stress symptoms (PTSS) in adolescent children; and (iii) associations between parents' illness characteristics and parent-adolescent communication. PATIENTS AND METHODS: A total of 212 adolescents completed the Impact of Event Scale and Parent-Adolescent Communication Scale. RESULTS: Adolescents communicated less openly with mothers with cancer than controls with mothers; this was the only significant difference with the reference group. Daughters communicated more openly with ill parents than with healthy parents. More open communication with healthy parents was related to fewer PTSS in daughters. More problem communication with both parents was related to more PTSS in both sons and daughters. Sons reported more problems in communication with ill parents in case of more intensive treatment or recurrent disease. Daughters experienced less open communication with both parents when ill parents received more intensive treatment. Time since diagnosis was not related to parent-adolescent communication. Multivariate analyses showed that communication patterns specifically affected PTSS of daughters. Problem communication with the healthy parent was the strongest predictor of intrusion while problem communication with the ill parents was the strongest predictor of avoidance. CONCLUSIONS: Parent-adolescent communication in families of cancer patients differs little from that in families not confronted with parental cancer. Problem communication outweighed lack of openness with respect to development of PTSS. Recurrent disease and intensive treatment regimens affected parent-adolescent communication negatively. 相似文献
107.
研究了由毕赤酵母胞内两步发酵法表达活性小分子阿片肽的条件.正交实验确定最佳生长条件为:甘油24g/L、酵母膏11g/L、蛋白胨22g/L、YNB 20ml/L,初始pH5.0.菌体密度可达2.46;以单因素实验确定最佳表达条件为:起始菌体浓度2.44,初始pH 6.25,每10h流加0.6%甲醇(v/v),表达时间96h.阿片肽250ml摇瓶产量由196mg/L提高至496mg/L. 相似文献
108.
2,3,4-三氟苯胺经与EMME缩合、环合、氟乙基化、与N-甲基哌嗪缩合和水解反应制得氟罗沙星,前4步反应可被离子溶剂1-丁基-3-甲基咪唑六氟磷酸盐促进,如环合反应温度由300℃降至200℃,总收率61%. 相似文献
109.
重组人胰高血糖素类多肽-1(7-36)对化学致糖尿病模型动物的降血糖作用 总被引:6,自引:0,他引:6
目的 本文研究了重组人胰高血糖素类多肽 1(7 36 )[rhGLP 1(7 36 ) ]对化学所致糖尿病模型动物的降血糖和促胰岛素分泌作用。方法 对四氧嘧啶型糖尿病小鼠及链脲霉素型糖尿病大鼠皮下注射不同剂量的rhGLP 1,分别于给药 4天后采血 ,收取血清 ,测定血糖及胰岛素值。结果 四氧嘧啶型糖尿病小鼠皮下注射 4 0、80 μg·kg-1rhGLP 1后 ,血糖值显著下降 (P <0 0 1) ,而 2 0 μg·kg-1剂量组则无显著性改变 ;链脲霉素型糖尿病大鼠皮下注射 2 8、5 6 μg·kg-1rhGLP 1后 ,血糖值显著下降 (P <0 0 5、P <0 0 1) ,而 14 μg·kg-1剂量组则无显著性改变。结论 rhGLP 1对实验动物部分 β细胞破坏的胰岛仍有促分泌胰岛素及降糖作用 相似文献
110.
D J van Drooge W L J Hinrichs K A M Wegman M R Visser A C Eissens H W Frijlink 《European journal of pharmaceutical sciences》2004,21(4):511-518
The aim of this study was to develop a dry powder formulation that stabilises the chemically labile lipophilic Delta(9)-tetrahydrocannabinol (THC), that rapidly dissolves in water in order to increase the bioavailability and that opens new routes of administration. It was investigated whether these aims can be achieved with solid dispersions consisting of a matrix of inulin, an oligo-fructose, in which THC is incorporated. These solid dispersions were prepared by lyophilisation of a solution of THC and inulin in a mixture of water and tertiary butyl alcohol (TBA). Both 4 and 8 wt.% of THC could be incorporated in a glassy matrix of inulin. In the solid dispersions only 0.4-0.5 wt.% of residual TBA was present after storage at 20 degrees C/45% relative humidity (RH) for 7 days. Unprotected THC was completely degraded after 40 days of exposure to 20 degrees C and 45% RH. However, solid dispersions exposed to the same conditions still contained about 80% non-degraded THC after 300 days. Dissolution experiments with tablets compressed from inulin glass dispersion material showed that THC and inulin dissolved at the same rate. Tablets weighing 125 mg and containing 2mg THC were prepared from a mixture of THC containing solid dispersion, polyvinylpolypyrrolidone (PVPP) and mannitol. Dissolution tests revealed that from these tablets 80% of the THC was dissolved within 3 min, which makes them promising for sublingual administration. It was concluded that THC can be strongly stabilized by incorporating it in a matrix of inulin. The aqueous dissolution rate was high which may improve bioavailability. 相似文献