全文获取类型
收费全文 | 7552篇 |
免费 | 815篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 28篇 |
儿科学 | 288篇 |
妇产科学 | 173篇 |
基础医学 | 1163篇 |
口腔科学 | 89篇 |
临床医学 | 996篇 |
内科学 | 1490篇 |
皮肤病学 | 116篇 |
神经病学 | 588篇 |
特种医学 | 405篇 |
外科学 | 910篇 |
综合类 | 154篇 |
一般理论 | 10篇 |
预防医学 | 820篇 |
眼科学 | 181篇 |
药学 | 536篇 |
中国医学 | 4篇 |
肿瘤学 | 427篇 |
出版年
2021年 | 92篇 |
2020年 | 66篇 |
2019年 | 107篇 |
2018年 | 120篇 |
2017年 | 100篇 |
2016年 | 119篇 |
2015年 | 110篇 |
2014年 | 165篇 |
2013年 | 235篇 |
2012年 | 350篇 |
2011年 | 333篇 |
2010年 | 222篇 |
2009年 | 170篇 |
2008年 | 343篇 |
2007年 | 379篇 |
2006年 | 363篇 |
2005年 | 321篇 |
2004年 | 310篇 |
2003年 | 276篇 |
2002年 | 246篇 |
2001年 | 243篇 |
2000年 | 240篇 |
1999年 | 217篇 |
1998年 | 119篇 |
1997年 | 89篇 |
1996年 | 91篇 |
1995年 | 83篇 |
1994年 | 84篇 |
1993年 | 60篇 |
1992年 | 186篇 |
1991年 | 179篇 |
1990年 | 177篇 |
1989年 | 183篇 |
1988年 | 146篇 |
1987年 | 157篇 |
1986年 | 151篇 |
1985年 | 153篇 |
1984年 | 69篇 |
1983年 | 98篇 |
1982年 | 58篇 |
1981年 | 55篇 |
1980年 | 71篇 |
1979年 | 85篇 |
1978年 | 53篇 |
1977年 | 64篇 |
1976年 | 72篇 |
1975年 | 70篇 |
1974年 | 71篇 |
1973年 | 80篇 |
1972年 | 60篇 |
排序方式: 共有8378条查询结果,搜索用时 12 毫秒
991.
CD44 is a marker of endocervical neoplasia. 总被引:2,自引:0,他引:2
E M Ibrahim A D Blackett J A Tidy M Wells 《International journal of gynecological pathology》1999,18(2):101-108
The expression of CD44s, CD44v4, CD44v5, CD44v7-8, and CD44v10 was investigated immunohistochemically in a variety of neoplastic cervical lesions. Normal endocervical columnar cells exhibited no reactivity for any of the antibodies, whereas the subcolumnar reserve cells were strongly positive for CD44s, CD44v5, and CD44v7-8. In some cases, positive cells were identified in the stroma surrounding the endocervical glands and adjacent to reserve cells. Cervical glandular intraepithelial neoplasia and adenocarcinoma showed consistent immunoreactivity for CD44v5. There was no significant change in CD44 immunoreactivity in squamous cell carcinoma compared with normal epithelia and cervical intraepithelial neoplasia. These findings lend support to the origin of carcinoma of the cervix from a common progenitor reserve cell and suggest the origin of reserve cells from the stroma. CD44v5 may be useful as a diagnostic marker of endocervical neoplasia and could provide a target for therapeutic approaches directed against specific epitopes. 相似文献
992.
993.
Biomarkers have long held out the promise that malignancies might be diagnosed early and that patients could be monitored more confidently during their clinical course to more reliably predict recurrence and the effect of therapy. Reliable tumor markers have been described for colon carcinoma, hepatomas, and other tumors, but no reliable marker has been identified to monitor the course of malignant melanoma. Recently, the plasma level of lipid-bound sialic acid (LASA-P) has been described as reflecting an alteration in the surface membrane of cancer cells. An attempt was made to correlate the LASA-P level, along with the serum level of neuron-specific enolase, a glycolytic enzyme specific to cells of neuroectoderm origin including melanocytes, with clinical disease activity with a follow-up to at least 2 years. Two hundred seventy patients had blood samples drawn at various times during their clinical course for assay of LASA-P and neuron-specific enolase. Eighty of the patients (30%) sampled developed a recurrence sometime during their clinical course, whereas another 10 patients had active disease noted at diagnosis with evaluative tumor markers. The sensitivity and specificity of neuron-specific enolase was 27% and 77%, respectively, and cannot be recommended as a marker for melanoma. LASA-P showed a sensitivity of 65%, with 55 patients recurring and having active disease with abnormally high markers and 35 patients recurring or having active disease with normal markers. Specificity of the LASA-P test was 76%. When recurrence was associated with elevated LASA-P levels, the elevated level preceded recurrence by a median of 9.3 months. LASA-P may be a useful marker to follow patients with malignant melanoma. 相似文献
994.
A new method of loading the lumbrical muscle in the cadaver hand, based on the bicycle brake cable concept, has been developed. The device can be inserted with the aid of tendon-tunneling forceps and sutured to the profundus tendon at the origin of the lumbrical muscle. Lumbrical function is stimulated by applying a force that approximates the attachment point on the profundus tendon to the lateral wing of the extensor expansion without predetermining which will move the origin, the insertion, or both. This preliminary study reports the use of this device in determining lumbrical length changes in five fresh cadaver hands as the index finger was passively moved through each of six standard finger positions. In the absence of other restraints lumbrical contraction causes the index finger to move from the claw position through the straight to the intrinsic position. The latter position represents maximum shortening. 相似文献
995.
Fetal, infant and childhood growth: relationships with body composition in Brazilian boys aged 9 years 总被引:2,自引:0,他引:2
Wells JC Hallal PC Wright A Singhal A Victora CG 《International journal of obesity (2005)》2005,29(10):1192-1198
BACKGROUND: Early growth rate has been linked to later obesity categorised by body mass index (BMI), but the development of body composition has rarely been studied. METHODS: We tested the hypotheses that (1) birthweight and weight gain in (2) infancy or (3) childhood are associated with later body composition, in 172 Brazilian boys followed longitudinally since birth. Growth was assessed using measurements of weight and height at birth, 6 months, and 1 and 4 y. Measurements at 9 y comprised height, weight and body composition using foot-foot impedance. RESULTS: Birthweight was associated with later height and lean mass (LM), but not fatness. Weight gain 0-6 months was associated with later height and LM, and with obesity prevalence according to BMI, but not with fatness. Weight gain 1-4 y was associated with later fatness and LM. Weight gain 4-9 y was strongly associated with fatness but not LM. Early growth rate did not correlate positively with subsequent growth rate. CONCLUSIONS: Early rapid weight gain increased the risk of later obesity, but not through a direct effect on fatness. Childhood weight gain remained the dominant risk factor for later obesity. The reported link between early growth and later obesity may be due partly to hormonal programming, and partly to the contribution of LM to obesity indices based on weight and height. Whether our findings apply to other populations requires further research. 相似文献
996.
D J Carini J V Duncia P E Aldrich A T Chiu A L Johnson M E Pierce W A Price J B Santella G J Wells R R Wexler 《Journal of medicinal chemistry》1991,34(8):2525-2547
A new series of nonpeptide angiotensin II (AII) receptor antagonists has been prepared. These N-(biphenylyl-methyl)imidazoles, e.g. 2-butyl-1-[(2'-carboxybiphenyl-4-yl)methyl]-4-chloro-5- (hydroxymethyl)imidazole, differ from the previously reported N-(benzamidobenzyl)imidazoles and related compounds in that they produce a potent antihypertensive effect upon oral administration; the earlier series generally were active only when administered intravenously. It has been found that the acidic group at the 2'-position of the biphenyl is essential. Only ortho-substituted acids possess both high affinity for the AII receptor and good oral antihypertensive potency. The carboxylic acid group has been replaced with a variety of acidic isosteres, and the tetrazole ring has been found to be the most effective. The tetrazole derivative, DuP 753, is currently in development for the treatment of hypertension. 相似文献
997.
OBJECTIVE: The purpose of this study is to validate the 4P's Plus screen for substance use in pregnancy. STUDY DESIGN: A total of 228 pregnant women enrolled in prenatal care underwent screening with the 4P's Plus and received a follow-up clinical assessment for substance use. Statistical analyses regarding reliability, sensitivity, specificity, and positive and negative predictive validity of the 4Ps Plus were conducted. RESULT: The overall reliability for the five-item measure was 0.62. Seventy-four (32.5%) of the women had a positive screen. Sensitivity and specificity were very good, at 87 and 76%, respectively. Positive predictive validity was low (36%), but negative predictive validity was quite high (97%). Of the 31 women who had a positive clinical assessment, 45% were using less than 1 day per week. CONCLUSION: The 4P's Plus reliably and effectively screens pregnant women for risk of substance use, including those women typically missed by other perinatal screening methodologies. 相似文献
998.
E A Lokey Z V Tran C L Wells B C Myers A C Tran 《Medicine and science in sports and exercise》1991,23(11):1234-1239
In this study, using meta-analysis the findings of all individual reports on the effects of exercise training on pregnancy outcomes were pooled to determine the effects of such training on the pregnant woman and her fetus. Meta-analysis is a statistical technique used to summarize the results of experimental studies that address a common problem. Results show that women who exercised during their pregnancies did not differ from sedentary women for any of the outcome variables measured: maternal weight gain (P = 0.07), infant birth weight (P = 0.20), length of gestation (P = 0.67), length of labor (P = 0.14), and APGAR scores (P = 0.59). Many of the exercise programs exceeded, without apparent adverse effects, the recommended limitations set by the American College of Obstetricians and Gynecologists. Overall, an exercise program using any of a variety of exercise modes that is performed for an average of 43 min.d-1, 3 times.wk-1, at a heart rate of up to 144 bpm, does not appear to be associated with adverse effects to the mother or fetus in a healthy normal pregnancy. However, these findings should be cautiously applied owing to the nature of the currently available data base. Recommendations or precautions for programs of greater intensities can not be made at this time. 相似文献
999.
1000.