全文获取类型
收费全文 | 45209篇 |
免费 | 3068篇 |
国内免费 | 1372篇 |
专业分类
耳鼻咽喉 | 115篇 |
儿科学 | 643篇 |
妇产科学 | 383篇 |
基础医学 | 5720篇 |
口腔科学 | 879篇 |
临床医学 | 3284篇 |
内科学 | 5130篇 |
皮肤病学 | 319篇 |
神经病学 | 4137篇 |
特种医学 | 1269篇 |
外国民族医学 | 3篇 |
外科学 | 1890篇 |
综合类 | 4043篇 |
现状与发展 | 2篇 |
一般理论 | 1篇 |
预防医学 | 4596篇 |
眼科学 | 262篇 |
药学 | 11034篇 |
12篇 | |
中国医学 | 3962篇 |
肿瘤学 | 1965篇 |
出版年
2024年 | 158篇 |
2023年 | 665篇 |
2022年 | 1299篇 |
2021年 | 1578篇 |
2020年 | 1442篇 |
2019年 | 1417篇 |
2018年 | 1382篇 |
2017年 | 1512篇 |
2016年 | 1449篇 |
2015年 | 1395篇 |
2014年 | 2321篇 |
2013年 | 3777篇 |
2012年 | 2098篇 |
2011年 | 2498篇 |
2010年 | 1755篇 |
2009年 | 2021篇 |
2008年 | 1979篇 |
2007年 | 1965篇 |
2006年 | 1685篇 |
2005年 | 1498篇 |
2004年 | 1303篇 |
2003年 | 1174篇 |
2002年 | 1042篇 |
2001年 | 978篇 |
2000年 | 737篇 |
1999年 | 738篇 |
1998年 | 732篇 |
1997年 | 644篇 |
1996年 | 616篇 |
1995年 | 663篇 |
1994年 | 519篇 |
1993年 | 488篇 |
1992年 | 490篇 |
1991年 | 446篇 |
1990年 | 422篇 |
1989年 | 420篇 |
1988年 | 369篇 |
1987年 | 366篇 |
1986年 | 336篇 |
1985年 | 460篇 |
1984年 | 417篇 |
1983年 | 291篇 |
1982年 | 370篇 |
1981年 | 285篇 |
1980年 | 297篇 |
1979年 | 216篇 |
1978年 | 224篇 |
1977年 | 168篇 |
1976年 | 197篇 |
1975年 | 84篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Jung Han Kim Sang Jun Lee Young Bok Han Jung Jo Moon Jong Bae Kim 《Archives of pharmacal research》1994,17(2):115-118
This paper describes the isolation of isoguanosine from Croton tiglium L. and its cytotoxic effect against several tumor cell lines in culture and newly reports that isoguanosine has an antitumor activity against implanted S-180 ascitic tumor mice. Isoguanosine is effective at the dose of 24 mg/kg/day x 5, with T/C value of 168%. Isoguanosine inhibits the growth of S-180 and Ehrlich solid tumor in mice at the optimal doses of 96 mg/kg/day x 12 and 48 mg/kg/day x 12, with 1-T/C values of 65% and 60%, respectively. 相似文献
62.
真皮下血管网岛状皮瓣抗菌力的实验研究 总被引:2,自引:0,他引:2
为研究真皮下血管网薄皮瓣用于感染创面的可行性,在家猪臀部两侧分别形成以旋髂深血管主干分支为蒂的传统岛状皮瓣和远侧50%修薄的真皮下血管网岛状皮瓣。用细菌计数、吖啶橙荧光染色测定白细胞吞噬指数和白细胞内杀菌率,应用激光多普勒、墨汁灌注、透明标本等方法,对两种皮瓣的抗菌力作自身对照研究。结果表明,真皮下血管网岛状皮瓣的抗菌力明显降低,可能与皮瓣修薄后血供减少,白细胞功能相应降低有关。 相似文献
63.
标记抗原在贮存过程中,由于受幅射分解和脱碘影响而使免疫活性和生物活性降低。我们对自制的~(125)碘-绒毛膜促性腺激素进行了实验观察。结果显示:贮存1月后,其免疫活性和生物活性分别降低了33.1%和44.0%;经电泳纯化后的标记物的免疫活性和生物活性明显提高,分别达到了最初的90.5%和95.3%。 相似文献
64.
以新鲜无壳牡蛎为原料,采用酶水解的方法制备牡蛎短肽,经SephadexG 15分离,并用HPLC测定其相对分子质量分布,通过HPLC法定量马尿酸测定各组分的ACE(血管紧张素转化酶)抑制活性。结果表明,牡蛎水解液中相对分子质量较大和较小部分的ACE抑制活性偏低,只有相对分子质量在一定范围内的短肽,对ACE具有较好的抑制作用,质量浓度为0.4mg/mL的牡蛎功能短肽的ACE抑制率为51.4%. 相似文献
65.
K. Jonderko A. Kasicka-jonderko B. Krusiec-świdergoł M. Dzielicki L. Strój M. Doliński K. Doliński B. Błońska-fajfrowska 《Neurogastroenterology and motility》2005,17(6):800-809
AIM: To check on reproducibility of parameters of the cutaneous electrogastrogram registered at a close or a distant time span. METHODS: Twenty-two volunteers recruited by an advertisement (11 females and 11 males, median age 25 years, range: 18-35) underwent three surface electrogastrography examinations of which two were taken on consecutive days and the third one was accomplished at least 2 weeks before or after the two other sessions. The examination involved a 30-min fasted recording, followed by a 90-min postprandial registration after intake of a 394-kcal mixed solid-liquid test meal. RESULTS: Parameters of the electrogastrogram pertaining to the frequency of the gastric slow waves exhibited good to moderate reproducibility, whereas fair reproducibility characterized parameters expected to describe the power of gastric slow waves. With the exception of the difference fed minus fasted power (DeltaDP), in no instance was the medium term reproducibility any worse than the short term one. Categorical data analysis revealed that the relative time share of normogastria postprandially exhibited a better reproducibility than in the fasted period. The Cohen's kappa-value of 0.459 for the DeltaDP for the medium term reproducibility placed this parameter within the range of moderate agreement between repeat examinations. Of the two two-parameter combinations considered, the alliance of the fasted and fed normogastria performed worse than any of those parameters considered alone, whereas a combination of the DeltaDP with the fed-state normogastria revealed a kappa-value amounting to 0.510 for the medium term reproducibility. CONCLUSIONS: The feasibility of some electrogastrographic parameters to convey clinically useful information may be hampered by their fair reproducibility. Recoding of parameters of the cutaneous electrogastrogram from primary continuous to secondary categorical may help achieve a better agreement between repeat examinations. 相似文献
66.
对不同来源的脂肪酶进行了系统的筛选,并根据位置专一性的差别将脂肪酶分为1,3 特异的、1,3 选择性和非选择性的3类.采用LipozymeRMIM在无溶剂系统中催化甘油、脂肪酸合成1,3 sn 甘油二酯.研究表明脂肪酸、底物醇种类、温度、水分活度对LipozymeRMIM的活力有明显的影响. 相似文献
67.
As an ongoing effort to elucidate the mechanisms involved in the calcium-dependent fertility regulation process, the viscoelastic properties of the mucus obtained from lamb cervix and human semen, as well as their water and total protein contents after exposure to EDTA, a chelating agent, or Nonoxynol-9 (N-9), a spermicidal agent, were examined. The viscosity was measured using a Cone Plate Digital Viscometer, while the water and total protein contents were determined by the lyophilization process and the Lowry method, respectively. The significant changes in the rheological properties of mucus, such as its viscosity and the water content, upon exposure to EDTA were demonstrated. The viscosity of cervical mucus and human semen were significantly increased by EDTA treatment (as compared to the controls): lamb cervical mucus (2.9 ± 0.3 vs. 2.2 ± 0.3 cps) and human semen (5.0 ± 0.3 vs. 4.3 ± 0.3 cps), respectively. The hydration rate was decreased by EDTA treatment as compared with the control (93.6 ± 0.7 vs. 96.8 ± 0.8%). Among tested samples, the reduction in the percentage of sperm penetration through the cervical mucus was the highest in the mucus containing EDTA, which had the lowest water content (93.6 ± 0.7%), indicating that there is a positive relationship between the hydration rate of the cervical mucus and its ability to permit the penetration of spermatozoa. This result indicates that spermicidal activity exerted by high concentrations of EDTA is in part due to its effect on the rheological properties of cervical mucus or semen. 相似文献
68.
Patientsfeelimpatientbecausetheycouldnotpredicttheonsettimeofepilepsy.Ifonsettimeofepilepsycouldbepreciselypredicted,thendrugadministrationanddisabilityofpreventionwillbecomeavailable.In1879,Echevarrzafoundonsettimeofepilepsyisdistributedaccordingtosomerules.Inrecentyears,scientistsperformalotstudiesinvolvingcytologyandmolecularbiologyofepilepsy.Clinicaldataindicatedonsetofepilepsyhascloserelationwithbiologicalrhythmsuchasawakeandsleepcycleandmenstrualcycle.Theobjectiveofthisstudy… 相似文献
69.
Martine Hascoët Michel Bourin Jacques Bradwejn 《Progress in neuro-psychopharmacology & biological psychiatry》1991,15(6):825-840
1. The mechanism of action of drugs might change according to the test used. Several noradrenergic drugs were tested in order to understand their implication in the mobility tests.
2. It was found that clonidine, an Alpha 2 agonist, acted differently according to the tast used. It provoked sedation in spontaneous activity test, and anti-immobility effects in the other tests.
3. Tall suspension test is able to show the double acting of clonidine.
4. Idazoxan might act either as an alpha 2 antagonist or as partial alpha 2 agonist. TST shown the unexpected partial alpha agonist effect of the molecule.
5. Forced swimming test is more specific for predicting antidepressant activity than tail suspension test which is close to a spontaneous activity model. 相似文献
70.
Using data from the National Health and Nutrition Examination Survey (NHANES II) 1976-1980, we demonstrate how cross-sectional total serum cholesterol surveillance data can be used by an individual to assess current and future personal cholesterol risk status. We propose statistical models, based on a person's current measured cholesterol level and the relationship between cross-sectional age and cholesterol percentile estimates, that will allow prediction of future cholesterol levels or the age at which specified cholesterol risk levels will be reached if no cholesterol-altering intervention is taken. These models incorporate the observed variation in the NHANES II data and expected intraperson biological variation and intralaboratory analytical variation. We illustrate the adequacy of the models using data from the longitudinal Framingham Study. 相似文献