全文获取类型
收费全文 | 573篇 |
免费 | 97篇 |
专业分类
670篇 |
出版年
2021年 | 6篇 |
2016年 | 8篇 |
2015年 | 9篇 |
2014年 | 14篇 |
2013年 | 19篇 |
2012年 | 14篇 |
2011年 | 14篇 |
2010年 | 13篇 |
2009年 | 21篇 |
2008年 | 20篇 |
2007年 | 23篇 |
2006年 | 17篇 |
2005年 | 17篇 |
2004年 | 16篇 |
2003年 | 21篇 |
2002年 | 24篇 |
2001年 | 23篇 |
2000年 | 18篇 |
1999年 | 24篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 10篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 12篇 |
1991年 | 13篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 12篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1974年 | 5篇 |
1973年 | 15篇 |
1972年 | 7篇 |
1971年 | 9篇 |
1970年 | 9篇 |
1969年 | 6篇 |
1967年 | 6篇 |
1966年 | 6篇 |
排序方式: 共有670条查询结果,搜索用时 0 毫秒
31.
32.
Restrictions on rotational and translational diffusion of pigment in the membranes of a rhabdomeric photoreceptor 下载免费PDF全文
Individual, isolated rhabdoms from dark-adapted crayfish (Orconectes, Procambarus) were studied with a laterally incident microbeam that could be placed in single stacks of microvilli. Concentration gradients of metarhodopsin along the lengths of microvilli were produced by local bleaches, accomplished by irradiation with small spots of orange light at pH 9 in the presence of glutaraldehyde or formaldehyde. No subsequent redistribution of pigment was observed in the dark, indicating an absence of translational diffusion. On the basis of comparison with other systems, glutaraldehyde, but not formaldehyde (0.75%), would be expected to prevent diffusion of protein in the membrane. Under the same conditions photodichroism is observed, indicating an absence of free Brownian rotation. Photodichroism is larger in glutaraldehyde than in formaldehyde, suggesting that the bifunctional reagent quiets some molecular motion that is present after treatment with formaldehyde. Quantitative comparison of photodichroism with mathematical models indicates that the pigment absorption vectors are aligned within +/- 50 degrees of the microvillar axes and are tilted into the surface of the membrane at an average value of about 20 degrees. The photoconversion of rhodopsin to metarhodopsin is accompanied by an increase in molar extinction of about 20% at the lambda maxand a reorientation of the absorption vector by several degrees. The transition moment either tilts further into the membrane or loses some of its axial orientation, or both. The change in orientation is 3.5 time larger in formaldehyde than in glutaraldehyde. 相似文献
33.
34.
Ori Eytan Fanny Morice-Picard Ofer Sarig Khaled Ezzedine Ofer Isakov Qiaoli Li Akemi Ishida-Yamamoto Noam Shomron Tomer Goldsmith Dana Fuchs-Telem Noam Adir Jouni Uitto Seth?J. Orlow Alain Taieb Eli Sprecher 《American journal of human genetics》2013,93(4):752-757
The coexistence of abnormal keratinization and aberrant pigmentation in a number of cornification disorders has long suggested a mechanistic link between these two processes. Here, we deciphered the genetic basis of Cole disease, a rare autosomal-dominant genodermatosis featuring punctate keratoderma, patchy hypopigmentation, and uncommonly, cutaneous calcifications. Using a combination of exome and direct sequencing, we showed complete cosegregation of the disease phenotype with three heterozygous ENPP1 mutations in three unrelated families. All mutations were found to affect cysteine residues in the somatomedin-B-like 2 (SMB2) domain in the encoded protein, which has been implicated in insulin signaling. ENPP1 encodes ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), which is responsible for the generation of inorganic pyrophosphate, a natural inhibitor of mineralization. Previously, biallelic mutations in ENPP1 were shown to underlie a number of recessive conditions characterized by ectopic calcification, thus providing evidence of profound phenotypic heterogeneity in ENPP1-associated genetic diseases. 相似文献
35.
Christopher M Grulke Kathleen Holm Michael-Rock Goldsmith Yu-Mei Tan 《Bioinformation》2013,9(13):707-709
As increasing amounts of biomonitoring survey data become available, a new discipline focused on converting such data into
estimates of chemical exposures has developed. Reverse dosimetry uses a pharmacokinetic model along with measured biomarker
concentrations to determine the plausible exposure concentrations-- a critical step to incorporate ground-truthing experimental
data into a distribution of probable exposures that reduces model uncertainty and variability. At the population level, probabilistic
reverse dosimetry can utilize a distribution of measured biomarker concentrations to identify the most likely exposure
concentrations (or intake doses) experienced by the study participants. PROcEED is software that provides access to probabilistic
reverse dosimetry approaches for estimating exposure distributions via a simple user interface.
Availability
PROcEED along with installation instructions is freely available for download from http://www.epa.gov/heasd/products/proceed/proceed.html 相似文献36.
37.
Herman Justin Park Brian Awsare Bharat West Frances Crittendon Denine Evans Lilah Harach Mary Karp Julie Peedin Alexis LaNoue Marianna Goldsmith Barbara Warnick Eugene Baram Michael 《BMC anesthesiology》2019,19(1):1-6
Hypoxic preconditioning (HPC) may protect multiple organs from various injuries. We hypothesized that HPC would reduce lung injury in patients undergoing thoracoscopic lobectomy. In a prospective randomized controlled trial, 70 patients undergoing elective thoracoscopic lobectomy were randomly allocated to the HPC group or the control group. Three cycles of 5-min hypoxia and 3-min ventilation applied to the nondependent lung served as the HPC intervention. The primary outcome was the PaO2/FiO2 ratio. Secondary outcomes included postoperative pulmonary complications, pulmonary function, and duration of hospital stay. HPC significantly increased the PaO2/FiO2 ratio compared with the control at 30 min after one-lung ventilation and 7 days after operation. Compared with the control, it also significantly improved postoperative pulmonary function and markedly reduced the postoperative hospital stay duration. No significant differences between groups were observed in the incidence of pulmonary complications or overall postoperative morbidity. HPC improves postoperative oxygenation, enhances the recovery of pulmonary function, and reduces the duration of hospital stay in patients undergoing thoracoscopic lobectomy. This study was registered in the Chinese Clinical Trial Registry (ChiCTR-IPR-17011249) on April 27, 2017. 相似文献
38.
39.
Nick V. Grishin Andrei L. Osterman Elizabeth J. Goldsmith Margaret A. Phillips 《Proteins》1996,24(2):272-273
Trypanosoma brucei ornithine decarboxylase, expressed and purified from E. coli, has been crystallized by the vapor diffusion method using PEG 3350 as a precipitant. The crystals belong to the monoclinic space group P21 and have cell constants of a = 66.3 Å, b = 151.8 Å, c = 83.7 Å, and β = 101.2°. While larger crystals are twinned, smaller crystals (0.4 × 0.3 × 0.05 mm3) are single. 相似文献
40.