全文获取类型
收费全文 | 18895篇 |
免费 | 1149篇 |
国内免费 | 85篇 |
专业分类
耳鼻咽喉 | 182篇 |
儿科学 | 600篇 |
妇产科学 | 416篇 |
基础医学 | 2488篇 |
口腔科学 | 371篇 |
临床医学 | 2190篇 |
内科学 | 4462篇 |
皮肤病学 | 527篇 |
神经病学 | 1892篇 |
特种医学 | 413篇 |
外科学 | 1449篇 |
综合类 | 103篇 |
一般理论 | 8篇 |
预防医学 | 1948篇 |
眼科学 | 305篇 |
药学 | 1279篇 |
中国医学 | 69篇 |
肿瘤学 | 1427篇 |
出版年
2024年 | 12篇 |
2023年 | 167篇 |
2022年 | 327篇 |
2021年 | 544篇 |
2020年 | 329篇 |
2019年 | 525篇 |
2018年 | 643篇 |
2017年 | 403篇 |
2016年 | 483篇 |
2015年 | 549篇 |
2014年 | 768篇 |
2013年 | 993篇 |
2012年 | 1563篇 |
2011年 | 1586篇 |
2010年 | 821篇 |
2009年 | 784篇 |
2008年 | 1292篇 |
2007年 | 1275篇 |
2006年 | 1237篇 |
2005年 | 1231篇 |
2004年 | 1059篇 |
2003年 | 1021篇 |
2002年 | 931篇 |
2001年 | 89篇 |
2000年 | 78篇 |
1999年 | 132篇 |
1998年 | 162篇 |
1997年 | 146篇 |
1996年 | 138篇 |
1995年 | 107篇 |
1994年 | 79篇 |
1993年 | 91篇 |
1992年 | 61篇 |
1991年 | 38篇 |
1990年 | 39篇 |
1989年 | 42篇 |
1988年 | 26篇 |
1987年 | 22篇 |
1986年 | 34篇 |
1985年 | 35篇 |
1984年 | 31篇 |
1983年 | 29篇 |
1982年 | 30篇 |
1981年 | 33篇 |
1980年 | 34篇 |
1979年 | 17篇 |
1978年 | 15篇 |
1976年 | 12篇 |
1974年 | 11篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Jordi Sabadell Jose Luis Sanchez-Iglesias Raquel Ferrer Teresa Higueras Jaume Alijotas Luis Cabero 《The journal of maternal-fetal & neonatal medicine》2007,20(5):423-425
Maternal group B streptococcal infection is an uncommon entity. Herein we describe a case of a 27-year-old-woman who presented life-threateniing group B streptococcus meningitis with an ectopic cervical pregnancy. No other infectious focus have been found. To our knowledge this is the first time that this association has been reported. 相似文献
32.
Scheila R Schaffazick Adriana R Pohlmann Teresa Dalla-Costa Sílvia S Guterres 《European journal of pharmaceutics and biopharmaceutics》2003,56(3):501-505
Different polymeric nanoparticles were freeze-dried and the powders compared to determine the influence of the lipophilic core (Miglyol 810) or benzyl benzoate) and polymeric material (poly(epsilon-caprolactone) or Eudragit S90) on their drug content and morphology. Diclofenac, a non-steroidal anti-inflammatory drug, was used as a model. To characterize the products, a biological experiment based on the evaluation of the mucosal toxicity of diclofenac was conducted. Nanocapsule and nanosphere suspensions were prepared by nanoprecipitation and freeze-dried after the addition of colloidal silicon dioxide. The powders were examined under scanning electron microscopy (SEM) and gastrointestinal tolerance of products was evaluated in rats. Powders presented drug contents between 90.2+/-5.5 and 101.1+/-1.9% (HPLC). SEM analyzes showed non-spherical microparticles and, at higher magnifications, the micro-powder surface presented a homogeneous nanocovering. Regarding the gastrointestinal tolerance, with the exception of benzyl benzoate-loaded formulations, powders presented lesional indexes lower than the diclofenac salt solution. In contrast to the literature, nanocapsules can be dried by freeze-drying without leakage of drug or breaking the capsule wall. 相似文献
33.
34.
Teresa Coccini Luciano Maestri Francesco S. Robustelli della Cuna L. Bin Lucio G. Costa Luigi Manzo 《Archives of toxicology》1996,70(11):736-741
Styrene is stereoselectively oxidized by cytochrome P450 to its reactive metabolite, styrene oxide. The (R)- and (S)-enantiomers
of styrene oxide can be conjugated with glutathione (GSH) to both (R)- and (S)-diastereoisomers of the specific mercapturic
acids, N-acetyl-S-(1-phenyl-2-hydroxyethyl)-L-cysteine (M1) and N-acetyl-S-(2-phenyl-2-hydroxyethyl)-L-cysteine (M2). Several investigations have indicated different toxic potential of the (R)- and (S)-configurations of styrene
oxide and its GSH- and N-acetyl-conjugates. In this study the mercapturic acid diastereoisomers were measured in the urine
of rats exposed to styrene in combination with ethanol, a good inducer of styrene metabolism. Male Sprague-Dawley rats were
given an isocaloric liquid diet containing ethanol (5% w/v) for 3 weeks. Starting from the 2nd week, the animals were also
exposed to styrene vapours (300 ppm, 6 h/day, 5 days/week) in a dynamic exposure chamber. Both the (R)- and (S)-diastereoisomers
of the M1 and M2 as well as the conventional biomarkers, mandelic acid (MA) and phenylglyoxylic acid (PGA) were measured in
urinary samples. Approximately 30 and 25% reduction of the levels of brain non-protein sulfhydryls (NPS) was observed in the
animals given styrene and ethanol, respectively, while the combined ethanol and styrene treatment resulted in a 60% decrease.
Ethanol consumption also resulted in higher urinary levels of the M1-R, M1-S and M2 metabolites associated with increased
M1-R/S ratio and higher urinary MA excretion compared to animals treated with styrene. These results suggest that the urinary
mercapturic acid diastereoisomers may be used as a noninvasive tool to examine stereoselective patterns of styrene metabolism
in vivo, as well as their alterations caused by ethanol. These compound-specific mercapturic acids may also be valuable indicators
of styrene-induced disorders of GSH homeostasis in nonaccessible organs.
Received: 19 December 1995/Accepted: 10 May 1996 相似文献
35.
Theresa Widrich M.D. Alexander W. Kennedy M.D. Teresa M. Myers M.D. William R. Hart M.D. Susan Wirth B.S.N. 《Gynecologic oncology》1996,61(3):304-308
Objective: To retrospectively review the management of adenocarcinomain situof the uterine cervix, to determine the outcome of conization versus hysterectomy, and to compare the results achieved by different methods of conization. Methods: We performed a retrospective pathology and chart review of 46 patients with cervical adenocarcinomain situfrom January 1980 to October 1994. Results: Nine patients were managed during the first half of the study period and 37 were managed in the second half. The mean age of patients was 38.4 years (range 25–72). Forty-five of 46 patients were diagnosed as a result of an abnormal Pap smear, although only 19 smears indicated adenocarcinomain situor other glandular abnormalities. Cold knife conization resulted in a 33% rate of positive margins for adenocarcinomain situcompared to 50% for large loop excision of the transformation zone (LLETZ). Among 24 conservatively managed patients with negative conization margins, there have been 2 (8.3%) recurrences of adenocarcinomain situ.Among patients not undergoing hysterectomy as definitive treatment, 1 of 18 (6%) patients undergoing cold knife conization recurred, compared to 4 of 14 (29%) managed with LLETZ, despite a 63.4-month shorter mean follow-up interval for the LLETZ patients. Conclusions: Cold knife conization is associated with a lower rate of recurrence of cervical adenocarcinomain situcompared to LLETZ. We recommend cold knife conization for patients who are not treated with hysterectomy. 相似文献
36.
Erik Diaz Teresa Gonzlez-Cossío Juan Rivera Maarten D. C. Immink Ruben Dario Mendoza C. Rafael Flores 《American journal of human biology》1991,3(5):525-530
This study aims at assessing the accuracy of estimates of body composition provided by bioimpedance (BIA) equations developed for U.S. populations when applied to a sample of Guatemalan farmers. If these equations were shown to have low validity, the second objective was to develop more accurate estimates of fat-free mass (FFM). One hundred males and females 19 to 45 years of age were randomly selected from four rural communities in the Western Highlands of Guatemala. Bioimpedance equations explained 59 and 33% of the variation in FFM, with a RMSE of 2.7 and 2.8 kg in males and females, respectively. Body fat (BF) predictions had a lower R2. Using the “all possible regressions” procedure, the best subset for prediction of FFM used anthropometric and BIA variables as predictors. The best model for men and women included only anthropometric variables: 75% of the variance in FFM for men and 70% of the variance in women was explained by this model. The RMSE was 2.1 and 1.9 kg for both groups, respectively. It is concluded that FFM can be estimated from anthropometric dimensions with a high degree of accuracy and use of BIA does not provide more valid estimates. 相似文献
37.
Laska M Fendt M Wieser A Endres T Hernandez Salazar LT Apfelbach R 《Physiology & behavior》2005,84(2):211-215
2,4,5-trimethylthiazoline (TMT) is a volatile component of the anal gland secretion of the red fox and elicits behavioral and physiological fear responses in the rat. Using instrumental conditioning paradigms, we determined olfactory detection thresholds for TMT in three rats, a natural prey species of the red fox, and compared their performance to that of three squirrel monkeys, three spider monkeys and four pigtail macaques, all non-prey species of the red fox. We found that the rats were able to discriminate concentrations between 0.04 and 0.10 ppt (parts per trillion) of TMT from the odorless solvent which is by far the lowest olfactory detection threshold for an odorant reported in rats so far. In contrast, the spider monkeys needed 0.14-1.38 ppb (parts per billion), the pigtail macaques 0.41-4.07 ppb, and the squirrel monkeys 4.07-13.80 ppb to detect TMT which does not rank among the lowest olfactory thresholds reported for these three primate species. Thus, these results support the assumption that the behavioral relevance of an odorant may be an important determinant of a species' olfactory sensitivity. 相似文献
38.
39.
Morphometric analysis of the superficial pineal gland of intact and blinded golden hamsters was conducted at both the light and electron microscopic level. The volume of the superficial gland was estimated to be 151 × 106 μm3, comprising 90–94% of the total pineal parenchymal tissue. Analysis of structural rhythms in animals maintained under a 14:10 L:D cycle showed significant 24-hr variations in values for pinealocyte nuclei, nucleoli, rough and smooth endoplasmic reticulum, Golgi bodies, dense bodies, and dense-cored vesicles. Peak values for these structures generally occurred at the light:dark interface. These results provide morphological correlates for known rhythmic variations in the synthesis of pineal-gland products. Superficial pineals examined 8 weeks following optic enucleation exhibited a decrease in the volume of pinealocyte nuclei and cytoplasm, while nucleolar size and the amounts of smooth and rough endoplasmic reticulum, Golgi bodies, dense bodies and dense-cored vesicles were enhanced. The latter changes are interpreted as indications of increased synthetic activity by the superficial pineal gland in response to light deprivation. 相似文献
40.
Alessandra Renieri Maria Teresa Bassi Lucia Galli Jing Zhou Marisa Giani Mario de Marchi Andrea Ballabio 《Human mutation》1994,4(3):195-198
Alport's syndrome is characterized clinically by a nonimmune glomerulopathy, often accompanied by sensorineural hearing loss and lens abnormalities, frequently due to mutations in the COL4A5 gene. The association of AS with diffuse leiomyomatosis, a benign proliferation of smooth muscle that occurs most often in the esophagus, trachea, and female genitalia, has been reported. Recently, a deletion involving both the COL4A5 and COL4A6 genes has been reported in four unrelated families. We report an additional case with Alport's syndrome associated with leiomyomatosis carrying a deletion of both COL4A5 and COL4A6 genes. A detailed characterization of the genomic region involved in the deletion event has been performed. Our results demonstrate that the deletion removed exon l of COL4A5 and exons l and 2 of COL4A6. © 1994 Wiley-Liss, Inc. 相似文献