全文获取类型
收费全文 | 708篇 |
免费 | 42篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 26篇 |
妇产科学 | 11篇 |
基础医学 | 179篇 |
口腔科学 | 10篇 |
临床医学 | 100篇 |
内科学 | 122篇 |
皮肤病学 | 7篇 |
神经病学 | 6篇 |
特种医学 | 134篇 |
外科学 | 54篇 |
综合类 | 15篇 |
预防医学 | 46篇 |
眼科学 | 3篇 |
药学 | 35篇 |
中国医学 | 1篇 |
肿瘤学 | 12篇 |
出版年
2021年 | 5篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 11篇 |
2016年 | 5篇 |
2015年 | 13篇 |
2014年 | 10篇 |
2013年 | 16篇 |
2012年 | 30篇 |
2011年 | 19篇 |
2010年 | 20篇 |
2009年 | 28篇 |
2008年 | 21篇 |
2007年 | 30篇 |
2006年 | 24篇 |
2005年 | 19篇 |
2004年 | 16篇 |
2003年 | 13篇 |
2002年 | 21篇 |
2001年 | 24篇 |
2000年 | 8篇 |
1999年 | 19篇 |
1998年 | 25篇 |
1997年 | 30篇 |
1996年 | 22篇 |
1995年 | 13篇 |
1994年 | 16篇 |
1993年 | 9篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 15篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 19篇 |
1986年 | 18篇 |
1985年 | 18篇 |
1984年 | 9篇 |
1983年 | 21篇 |
1982年 | 21篇 |
1981年 | 18篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 12篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1972年 | 4篇 |
1968年 | 3篇 |
排序方式: 共有764条查询结果,搜索用时 15 毫秒
1.
2.
3.
Perfluorochemicals as US contrast agents for tumor imaging and hepatosplenography: preliminary clinical results 总被引:3,自引:0,他引:3
Mattrey RF; Strich G; Shelton RE; Gosink BB; Leopold GR; Lee T; Forsythe J 《Radiology》1987,163(2):339-343
In animals, perfluorochemicals (PFCs) are effective ultrasound (US) contrast agents that produce hepatic, splenic, and tumor enhancement. The use of Fluosol-DA 20%, an emulsion of perfluorodecalin and perfluorotripropylamine, was studied in nine non-critically ill patients with cancer who had liver lesions. US studies without Fluosol were compared with studies obtained 24, 48, and 72 hours after Fluosol infusion. Vital signs and extensive laboratory analyses are performed before and after Fluosol infusion. Liver metastases from colonic, pancreatic, and gastric carcinoma exhibited rim or diffuse enhancement after a Fluosol dose of 1.6 g/kg or greater. Fluosol produced echogenic enhancement of the liver and spleen relative to kidney at a dose of 2.4 g/kg, allowing the detection of nonenhancing lesions. In addition, Fluosol at a dose of 1.6 g/kg or greater allowed detection of lesions not seen before contrast medium was administered in three of the seven patients studied. There was a mild increase in the level of serum glutamic oxaloacetic transaminase in two patients, one given 2.4 and the other 3.2 g/kg of Fluosol. Mild and transient allergic reactions without change in vital signs were experienced by two patients. 相似文献
4.
5.
6.
Daniel L. Hamilos MD John J. Oppenheimer MD Harold S. Nelson MD Sally Wenzel MD Sue Driscoll RN Richard F. Lockey MD David B. K. Golden MD Leland Fan MD Ralph J. Sanks RPh S. Allen Bock MD John W. Yunginger MD Donald Stevenson MD Timothy Sullivan MD Thomas Corbridge MD 《The Journal of allergy and clinical immunology》1993,91(6)
These guidelines are intended to reduce the potential for serious or life-threatening reactions when clinical research is conducted. The following issues were addressed: identifying the risks involved in the research, providing adequate safeguards in the protocol design and during withholding of medication, anticipating risks, minimizing the chances for human error, providing resuscitative equipment sufficient to deal with the most serious anticipated life-threatening reactions, planning for medical support in case of a life-threatening emergency, and optimizing the use of medical personnel and expertise to handle emergency situations. The guidelines also discuss important general issues about protocol design and implementation and the human subject consent form, which should facilitate the approval of protocols by the governing institutional review board.The guidelines are not meant to be inflexible or applicable to all research situations. However, it is our hope that they will allow for clinical research to be conducted in a manner that affords the research subjects a high degree of protection from unnecessary and possibly fatal injuries. 相似文献
7.
Dohle GR; Ramos L; Pieters MH; Braat DD; Weber RF 《Human reproduction (Oxford, England)》1998,13(3):620-623
Male genital tract obstructions may result from infections, previous
inguinal and scrotal surgery (vasectomy) and congenital bilateral absence
of the vas deferens (CBAVD). Microsurgery can sometimes be successful in
treating the obstruction. In other cases and in cases of failed surgical
intervention, the patient can be treated by microsurgical or percutaneous
epididymal sperm aspiration (MESA, PESA) or testicular sperm extraction
(TESE) and intracytoplasmic sperm injection (ICSI). We present the results
of 39 ICSI procedures for obstructive azoospermia in 24 couples. The
aetiology of the obstruction was failed microsurgery in 11 patients, CBAVD
in nine and genital infections in four. Sperm retrieval was accomplished
via MESA in four cases, PESA in 18 cases and via TESE in 11 cases. TESE was
only applied when PESA failed to produce enough spermatozoa for
simultaneous ICSI. In six patients, the ICSI procedure was performed with
cryopreserved spermatozoa after an initial PESA procedure. Fertilization
occurred in 47% of the metaphase II oocytes; embryo transfer was performed
in 92% of procedures and resulted in a clinical pregnancy in 13/39
procedures. Ongoing pregnancy was achieved in 10/39 procedures. One
pregnancy was terminated early after prenatal investigation showed a
cytogenetic abnormality (47,XX+18, Edwards syndrome). The other nine
pregnancies resulted in the live birth of 10 children, without any
congenital abnormalities. Epididymal and testicular retrieved spermatozoa
were successfully used for ICSI to treat obstructive azoospermia, and
resulted in an ongoing pregnancy in 10 of 24 couples (41.6%) after 39 ICSI
procedures, a success rate of 25.6% per treatment cycle and of 27.7% per
embryo transfer.
相似文献
8.
9.
Sensitization to soybean hull allergens in subjects exposed to different levels of soybean dust inhalation in Argentina 总被引:2,自引:0,他引:2
Codina R Ardusso L Lockey RF Crisci C Bertoya N 《The Journal of allergy and clinical immunology》2000,105(3):570-576
BACKGROUND: Soybean hulls (SHs) have been identified as the source of aeroallergens responsible for soybean asthma outbreaks. However, the prevalence of sensitization to SH allergens in subjects from Argentina, a country where soybeans are produced, is unknown. OBJECTIVE: The purpose of this study was to determine the prevalence of sensitization to SH by in vivo and in vitro tests in subjects with asthma or allergic rhinitis and in control subjects from Argentina who have been exposed to different levels of soybean dust inhalation (SDI). METHODS: Exposure to SDI is defined as follows: (1) direct = occupational, (2) indirect = proximity to soybean fields or grain elevators, and (3) urban = urbanized areas without a known source of SDI. Two groups were studied. Group 1 consisted of 365 subjects with asthma or allergic rhinitis and group 2 (control group) of 50 healthy individuals. Subjects from both groups were classified according to their exposure to SDI. All subjects completed standard questionnaires. Prick skin tests (STs) with an SH extract and with common allergens were performed on all subjects. Specific IgE and IgG4 to SH were measured in sera of 51 of 56 subjects from group 1 who had a positive ST to SH and in all sera from group 2. RESULTS: Fifty-six (15.3%) subjects from group 1 and no subjects from group 2 had a positive ST to SH (wheal SH/wheal histamine >/=0.5). In group 1, positive STs to SH were 38.7%, 20.3%, and 8.2% in subjects with direct, indirect, and urban exposures, respectively (P <.001). Monosensitization to SH is absent in all subjects from group 1. The percent of subjects with positive STs to mites, pollen, and molds was highest in those with a positive ST to SH versus those with a negative ST to SH (P <.01). Asthmatic patients with a positive ST to SH, compared with those exclusively sensitized to mites, had a higher frequency of daily or weekly symptoms (59.4% vs 25.7%, respectively, P <.001) and a higher percent of glucocorticoid dependence (52.8% vs 34%, respectively, P <.01). Percent positive IgE in group 1 and group 2 were 39.2% and 10% (P <.001) and percents positive IgG4 are 27.4% and 12%, respectively (not significant). In subjects from group 1 and group 2 with direct exposure percents positive IgE are 58.3% and 13.3% (P < .001) and percents positive IgG4 were 75% and 20%, respectively (P < .02). IgG4 in group 1 was significantly higher in subjects with direct exposure compared with subjects with indirect or urban exposure. CONCLUSION: This study demonstrated that there was (1) a high prevalence of sensitivity to SH in subjects with asthma or allergic rhinitis from Argentina and (2) an association between sensitivity to SH and severity of asthma and level of exposure to SDI. 相似文献
10.
L1 knockout mice show dilated ventricles, vermis hypoplasia and impaired exploration patterns 总被引:8,自引:3,他引:8
Fransen E; D'Hooge R; Van Camp G; Verhoye M; Sijbers J; Reyniers E; Soriano P; Kamiguchi H; Willemsen R; Koekkoek SK; De Zeeuw CI; De Deyn PP; Van der Linden A; Lemmon V; Kooy RF; Willems PJ 《Human molecular genetics》1998,7(6):999-1009
L1 is a neural cell adhesion molecule mainly involved in axon guidance and
neuronal migration during brain development. Mutations in the human L1 gene
give rise to a complex clinical picture, with mental retardation,
neurologic abnormalities and a variable degree of hydrocephalus. Recently,
a transgenic mouse model with a targeted null mutation in the L1 gene was
generated. These knockout (KO) mice show hypoplasia of the corticospinal
tract. Here we have performed further studies of these KO mice including
magnetic resonance imaging of the brain, neuropathological analysis and
behavioral testing. The ventricular system was shown to be abnormal with
dilatation of the lateral ventricles and the 4th ventricle, and an altered
shape of the Sylvius aqueduct. Additionally, the cerebellar vermis of the
KO mice is hypoplastic. Their exploratory behavior is characterized by
stereotype peripheral circling reminiscent of that of rodents with induced
cerebellar lesions.
相似文献