全文获取类型
收费全文 | 3686篇 |
免费 | 279篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 261篇 |
妇产科学 | 117篇 |
基础医学 | 564篇 |
口腔科学 | 40篇 |
临床医学 | 369篇 |
内科学 | 810篇 |
皮肤病学 | 18篇 |
神经病学 | 398篇 |
特种医学 | 124篇 |
外国民族医学 | 1篇 |
外科学 | 404篇 |
综合类 | 57篇 |
一般理论 | 3篇 |
预防医学 | 268篇 |
眼科学 | 119篇 |
药学 | 134篇 |
中国医学 | 2篇 |
肿瘤学 | 237篇 |
出版年
2023年 | 24篇 |
2022年 | 38篇 |
2021年 | 86篇 |
2020年 | 50篇 |
2019年 | 77篇 |
2018年 | 91篇 |
2017年 | 56篇 |
2016年 | 66篇 |
2015年 | 64篇 |
2014年 | 92篇 |
2013年 | 109篇 |
2012年 | 204篇 |
2011年 | 207篇 |
2010年 | 116篇 |
2009年 | 77篇 |
2008年 | 153篇 |
2007年 | 153篇 |
2006年 | 146篇 |
2005年 | 125篇 |
2004年 | 138篇 |
2003年 | 125篇 |
2002年 | 102篇 |
2001年 | 99篇 |
2000年 | 112篇 |
1999年 | 97篇 |
1998年 | 41篇 |
1997年 | 32篇 |
1996年 | 31篇 |
1995年 | 30篇 |
1994年 | 30篇 |
1993年 | 28篇 |
1992年 | 87篇 |
1991年 | 88篇 |
1990年 | 59篇 |
1989年 | 60篇 |
1988年 | 62篇 |
1987年 | 61篇 |
1986年 | 64篇 |
1985年 | 54篇 |
1984年 | 36篇 |
1983年 | 44篇 |
1982年 | 23篇 |
1981年 | 28篇 |
1979年 | 37篇 |
1978年 | 26篇 |
1977年 | 33篇 |
1974年 | 24篇 |
1926年 | 23篇 |
1925年 | 28篇 |
1924年 | 22篇 |
排序方式: 共有3980条查询结果,搜索用时 31 毫秒
101.
Diagnostic accuracy of oropharyngeal cultures in infants and young children with cystic fibrosis. 总被引:3,自引:0,他引:3
M Rosenfeld J Emerson F Accurso D Armstrong R Castile K Grimwood P Hiatt K McCoy S McNamara B Ramsey J Wagener 《Pediatric pulmonology》1999,28(5):321-328
The objective of this study was to assess the diagnostic accuracy of oropharyngeal (OP) cultures relative to simultaneous bronchoalveolar lavage (BAL) cultures in very young children with CF, and to examine the effects of bacterial density, age, and study cohort on diagnostic accuracy. Respiratory culture data were analyzed from three independent, prospective studies involving simultaneous collection of 286 OP and BAL cultures from 141 children with CF <5 years of age. For predicting any growth of Pseudomonas aeruginosa (Pa) from the lower airway in subjects =18 months of age (mean age, 8 +/- 5 months), OP cultures had a sensitivity of 44% (95% CI 14%, 79%), specificity of 95% (90%, 99%), positive predictive value of 44% (14%, 79%), and negative predictive value of 95% (90%, 99%). Diagnostic accuracy was similar for Haemophilus influenzae (Hi). Specificity was significantly lower for Staphylococcus aureus (Sa). Sensitivity for all organisms improved if a positive lower airway culture was defined as >/=10(3) or >/=10(5) cfu/mL. Specificity for Pa declined significantly with increasing age. In children with CF <5 years of age, the specificity and negative predictive value of OP cultures for Pa are high, while the sensitivity and positive predictive value are poor. Thus, in this age range, a negative throat culture is helpful in "ruling out" lower airway infection with Pa. However, a positive culture does not reliably "rule in" the presence of Pa in the lower respiratory tract. These findings may have implications for study design and interpretation as well as clinical management of young children with CF. 相似文献
102.
103.
Pax6 is essential for establishing ventral-dorsal cell boundaries in pituitary gland development 总被引:7,自引:0,他引:7 下载免费PDF全文
104.
Growth hormone mediates the growth of T-lymphoblast cell lines via locally generated insulin-like growth factor-I 总被引:3,自引:0,他引:3
M E Geffner N Bersch B M Lippe R G Rosenfeld R L Hintz D W Golde 《The Journal of clinical endocrinology and metabolism》1990,71(2):464-469
It has become evident that locally produced insulin-like growth factors-I and -II (IGF-I and IGF-II) play an important role in the medication of GH action upon tissues. To explore this concept with respect to immunocompetent cells, we analyzed IGF production and clonogenic responsiveness of immortalized human T-cell lines established from seven normal controls and four Laron dwarfs. While the normal T-cell lines showed significant augmentation of basal colony formation in response to both IGF-I and GH, little increase in clonogenesis in response to GH was seen with the Laron T-cell lines. Assay of basal and GH-stimulated conditioned media demonstrated low, but measurable, levels of IGF-I and IGF-II from both normal and Laron T-cells. Under serum-free incubation conditions, GH stimulation of normal T-cell lines failed to generate significant increases in mean IGF-I or IGF-II concentration and no increase in the mean IGF-II concentration in conditioned medium were observed after GH stimulation of Laron T-cell lines. Nevertheless, the increased cloning efficiency of the normal T-cell lines in response to either GH or IGF-I was nearly completely abrogated by preincubation of cells with antibodies to either IGF-I or the type I IGF receptor. These studies, thus, support a role for locally generated IGF-I in the mediation of GH action on T-lymphocytes and indicate that this effect is mediated via the type I IGF receptor. 相似文献
105.
The neonatal period is a time of transition between pituitary-independent fetal growth and the pituitary-dependent growth seen in older mammals. To evaluate pituitary-dependent neonatal growth, Wistar rats were hypophysectomized (Hx) on postnatal day 6. Nineteen days post-Hx, body weight and tail length were inhibited 48% and 34%, respectively, compared with sham-Hx controls. Organ weights determined on days 10, 15, 20, 25, and 30 revealed three patterns of pituitary-dependence: 1) pituitary-independent growth in the brain and lung; 2) moderate pituitary-dependent growth in the heart, liver, kidney, and intestine; and 3) marked pituitary-dependent growth in the adrenals, spleen, and testes. Both serum insulin-like growth factor (IGF)-I and -II levels fell significantly in Hx pups by 54 h after Hx (P = 0.0005), and Northern analysis on day 15 showed a significant decrease in liver messenger RNA (mRNA) for IGF-II. Analysis of the major IGF binding proteins (BPs) was performed by Western ligand blots. Hx performed on day 6 resulted in a linear decrease in the amount of the 22k BP from day 10 to day 30. In contrast, the major neonatal BP (IGFBP-2, a 29.5k molecule) showed a biphasic response to neonatal Hx. On postnatal day 10, 4 days after Hx, a significant decrease in IGFBP-2 occurred, which persisted through day 15; by postnatal day 20 and continuing through postnatal day 30, the amount of IGFBP-2 in the serum dramatically increased. The 40 to 50k fraction of IGFBP-3 first appeared in significant quantities by postnatal day 20, and after Hx dropped to 10% of sham-control values. Similarly, Northern analysis on day 15 demonstrated a significant decrease in liver, but not brain, mRNA for IGFBP-2 after Hx, whereas on postnatal day 25, liver mRNA for IGFBP-2 was increased in Hx pups compared with sham controls. We conclude that the pituitary gland exerts significant but selective effects on neonatal growth, with the notable exception of brain growth. Serum levels of both IGF-I and IGF-II, as well as their BPs, are pituitary dependent in the neonatal period. Pituitary-dependent neonatal growth thus appears to be mediated by IGF and modulated by IGF-binding proteins. On the other hand, that portion of the persistent growth in the neonatal Hx rat that is independent of the pituitary-IGF axis may be a good model for investigation of fetal growth. 相似文献
106.
We investigated pituitary regulation of growth during two critical stages of development in the rat, using hypophysectomy (Hx) with replacement of GH and/or T4. In the neonatal period (Hx on day 6), body weight and tail length were inhibited by 60% and 50%, respectively, while these parameters were inhibited by 80% and 85% by Hx in the juvenile period (Hx on day 45). Administration of T4 alone significantly increased skeletal growth (tail length) in neonatal Hx rats, while T4 alone proved ineffective in promoting somatic growth in juvenile Hx rats. GH effects were greater on body weight than on tail length at both stages of development. Replacement of both GH and T4 restored somatic growth to normal values during both time periods. The brain was the sole organ whose growth appeared to be independent of the pituitary. Hx reduced serum insulin-like growth factor-I (IGF-I) and -II in both age groups, and GH alone restored IGF-I and -II levels to the control range. The major IGF-binding proteins (IGFBPs) were analyzed by Western ligand blots. The effect of Hx on the predominant IGFBP was greater in the juvenile rat. T4 replacement in the neonate and GH replacement in the juvenile rat restored IGFBPs to control levels. We conclude that somatic growth in the rat is less pituitary dependent in the neonatal period. There are also important age-specific differences in organ response to GH and T4. Serum IGFs and their binding proteins are pituitary dependent even in infancy, and GH is their primary regulator. The neonatal Hx rat is an important model for the study of the dynamic development of the pituitary-dependent growth. 相似文献
107.
108.
Charlène Aubinet Helena Cassol Olivier Bodart Leandro R.D. Sanz Sarah Wannez Charlotte Martial Aurore Thibaut Géraldine Martens Manon Carrière Olivia Gosseries Steven Laureys Camille Chatelle 《Annals of physical and rehabilitation medicine》2021,64(5):101432
BackgroundThe Coma Recovery Scale-Revised (CRS-R) is the gold standard to assess severely brain-injured patients with prolonged disorders of consciousness (DoC). However, the amount of time needed to complete this examination may limit its use in clinical settings. Objective. We aimed to validate a new faster tool to assess consciousness in individuals with DoC.MethodsThis prospective validation study introduces the Simplified Evaluation of CONsciousness Disorders (SECONDs), a tool composed of 8 items: arousal, localization to pain, visual fixation, visual pursuit, oriented behaviors, command-following, and communication (both intentional and functional). A total of 57 individuals with DoC were assessed on 2 consecutive days by 3 blinded examiners: one CRS-R and one SECONDs were performed on 1 day, whereas 2 SECONDs were performed on the other day. A Mann-Whitney U test was used to compare the duration of administration of the SECONDs versus the CRS-R, and weighted Fleiss’ kappa coefficients were used to assess inter-/intra-rater reliability as well as concurrent validity.ResultsIn the 57 participants, the SECONDs was about 2.5 times faster to administer than the CRS-R. The comparison of the CRS-R versus the SECONDs on the same day or the best of the 3 SECONDs led to “substantial” or “almost perfect” agreement (kappa coefficients ranging from 0.78 to 0.85). Intra-/inter-rater reliability also showed almost perfect agreement (kappa coefficients from 0.85 to 0.91 and 0.82 to 0.85, respectively).ConclusionsThe SECONDs appears to be a fast, reliable and easy-to-use scale to diagnose DoC and may be a good alternative to other scales in clinical settings where time constraints preclude a more thorough assessment. 相似文献
109.
110.